How to Record Classroom Lectures

Written by admin on December 12, 2009 - 1 Comment

Got an important lecture coming up that you’d like to record? Here are 4 easy ways to make sure you get a good recording -

1. Get a good recording device

Ideally get a Digital Voice Recorder with a USB port to attach an external microphone. This device will not only help you get a great quality recording but will also make it easy for you to later transfer the recording to a computer or laptop for reviewing, transcribing, editing, sharing, etc. See How To Choose A Digital Voice Recorder for more on this.

You can also use your laptop’s in-built recording software.

2. Get an external microphone

This is extremely important if you want to get a clear recording in a classroom that’s full of background noise and chatter. The inbuilt microphone of a DVR or laptop just isn’t powerful enough to get a good recording in such a setting.

What you’ll need is an external, unidirectional, cardioid microphone with a USB connector that can be easily connected to your DVR or laptop.

The microphone should be unidirectional because you don’t want the noise in the classroom or the clickity click from your laptop to be recorded. It should be Cardioid because that’s the best kind of unidirectional microphone for recording speech.

If you’re planning to use your laptop’s recording software then it’s advisable to get a clip or mount to attach the microphone to the laptop or the front of your desk so that your hands are free to type and take notes.

3. Place the recording device close to the speaker

If you use your laptop, try grab a seat in the front row so that you’re close to the speaker – that way you’ll get the best sound quality. Though it’s still possible to get a decent recording even if you’re sitting in the middle of the room and use an external microphone. If you use a DVR, place it as near the speaker as possible.

4. Take notes!

Okay so why should you take notes if you’re recording the lecture? Because when you sit down to hear the recording or send it to your transcriptionist for transcribing, the notes will help decipher any technical terms or particularly difficult parts of the lecture.

That’s it! If you take care of these four things, you’re all set to get a great recording of that lecture.

And for the visual learners amongst you, here’s a neat demonstration of the the SP-USB-MIC-1: Miniature USB Microphone (This one’s  omnidirectional but gives decent quality. Try getting a unidirectional one though – that’s better for lectures).

Happy recording!

1 Comment

Using Directional Microphones for Recording Speech

Written by admin on November 7, 2009 - 1 Comment

A microphone can pick up sounds from all directions or a specific direction depending on its technical built. This sensitity to sound from one or more directions is called Directionality. Based on this property, there are 3 main types of microphones available -

Omnidirectional Microphones

Unidirectional Microphones

Bidirectional Microphones

Omnidirectional Microphones

These microphones pick up sounds from all directions and are generally used only when there are multiple speakers involved in a recording (as would be in the case of a conference or meetings).

These microphones are not recommended for recording the speech of a single speaker unless you’re recording in a quite room with little or no surrounding noise. This is because omnidirectional microphones capture sounds from all directions and therefore a lot of unwanted sounds such as shifting chairs, doors opening, side conversations, vehicles passing by, etc. can also get recorded.

When using an omnidirectional microphone in an indoors setting, it’s a good idea choose a quiet room and lay down some ground rules for the participants before beginning recording. When outdoors, the microphone should be placed as close to the speaker as possible.

Unidirectional Microphones

These microphones pick up sounds from a single direction – i.e. the direction they’re facing. There are 2 major types of unidirectional microphones -

Shotgun Microphones

Shotgun microphones are best for outdoor recordings because they have a very narrow ‘angle of acceptance’ or ‘pickup pattern’ or simply put, the area from which they pick up sound. This means they can pick up the particular sound they’re directly towards and reject all other surrounding noise to produce a very clear recording.

Long shotgun microphones provide the highest level of directionality and pick up sound from only the person/object that they’re pointed at. This leads to a very high quality of recording and makes them ideal for noisy locations.

The downside of using these microphones is that since they’re very long (and often used with a boom), they normally need a second person to operate. Also, the microphone must consistently be pointed directly towards the speaker – any movement away from the speaker will result in an interruption of the flow of sound to the microphone and thereby impact the recording.

Short shotgun microphones are, well, shorter. Their properties are similar to the long shotgun microphones, the only difference lying in the slightly wider ‘angle of acceptance’ of the short shotgun. They are more portable as well; this makes them the microphones of choice for outdoor recordings that require a degree of mobility – such as interviews conducted on the street.

Shotgun microphones are especially useful when the speaker is not close to the microphone. The more the distance between the speaker and the microphone, the more directional the microphone needs to be.

Cardioid Microphones

Cardioid microphones are the ones used most commonly for speech recording. That’s because they are directional like the shotgun microphones yet offer flexibility in terms of the ‘angle of acceptance’ as well as size and portability.

They pick up sound mainly from the direction that they’re pointed in, some from the far sides of the microphone, and very little from behind the microphone. Since they’re unidirectional, they eliminate a lot of surrounding noise and produce high quality recordings.

Bidirectional Microphones

As the name suggests, these bidirectional microphones pick up sounds from two opposite directions and reject sound from other sides. Also known as figure-of-eight microphones, these microphones are useful for recording two-person interviews where two people are seated on the opposite sides of a table. Bidirectional microphones are not very commonly used because of their limited application.

Some microphones come with multiple options that allow users to switch from let’s say cardioid to omnidirectional mode when required.

1 Comment

Microphones: Reading the spec sheet

Written by admin on November 3, 2009 - 0 Comments

Are you planning to record an interview, lecture, teleseminar, conference, or some other event involving speech?  It’s been said that a recording can only be as good as the microphone that’s used – and the statement is absolutely true. Choosing the right microphone is as crucial as choosing the right recording device.
The choice of microphone for a recording depends on several factors such as location (indoors/outdoors), number of speakers, distance of the microphone from the speaker/s, etc. In this post we’ll look at some key properties of a microphone that should be considered before making a purchase.
Diaphragms
Every microphone has diaphragm i.e. a thin membrane of plastic, aluminium, or paper located in the head of the microphone that vibrates when hit by sound waves. Vibration of the diaphragm leads to movement in other parts of the microphone that generate electrical signals (or audio signals) that can be recorded. We’ll discuss the ‘other parts’ and their movement in a minute. There are 3 types of diaphragms – large, medium, and small – that differ in diameter.
Large diaphragms have diameters ranging from 3/4 inch upto to 1 inch and sometimes more. Their large surface area and comparitively flexible surface makes them more sensitive to sound. Because of their construct, they also have lesser ‘self-noise’ i.e. noise added to the recording by the microphone’s internal sounds. But while the general sound quality is quite decent, they don’t capture higher frequencies very well.
Small diaphragms (with diameters 5/8 inch or less) are lighter and therefore more responsive to higher frequencies. When sound waves strike a diaphragm from the side, they take time to travel across it’s body. If the diaphragm is large, the time taken to travel across will be longer and may result in loss of vibrations leading to reduced quality. That’s why large diaphragms work best when the sound waves strike from directly in front rather than the sides. With small diaphragms the loss of vibrations is negligible and therefore the sound quality is sharper no matter which direction the sound is coming from.
Transducers
A transducer is a device that converts one form of energy to another. Tehcnically speaking, microphones are transducers that convert accoustic energy (sound waves) to electrical energy. Based on the kind of transducer used, there are 4main types of microphones available – Dynamic, Condenser, Ribbon, and Crystal. Dynamic and Condenser are the most widely used.
Dynamic Microphones
These simple, rugged microphones work on the principle of electromagnetism. When sound waves hit the the diaphragm of a dynamic microphone, the vibration makes a coil of wire (or a ribbon of metallic foil) move back and forth against a fixed magnet. This creates electric current or audio signals that can be recorded.
Dynamic microphones are simply constructed and sturdy. They don’t require an external battery or other power source to operate and compartively less expensive. They can handle high sound pressure levels without distortion but can’t capture high frequencies very well due to their mechanical construct. Ideal for rough use in live performances and on location recordings.
Condenser Microphones
These sensitive microphones work on the principle of capacitance (the ability of a body to hold electrical charge). Condenser (aka capacitor) microphones consist of two plates formed by a thin conductive diaphragm and a metallic back plate – these together form a capacitor. A fixed charge is placed across this capacitor through an external power source such as a battery or a phantom power supply. When the diaphragm vibrates under the force of sound waves, there are fluctuations in the capacitance leading to changes in voltage between the plates (voltage being inversely propotional to capacitance and capacitance being inversely proportional to the distance between the plates). These changes in voltage can then be recorded.
Condenser microphones are sensitive to a wider range of frequencies and can pick up softer sounds. They also have a flatter frequency response. The downside is that they are fragile and therefore unsuitable for rough use. They are also quite expensive. Best for in studio or home recordings.
Directionality
A microphone can pick up sounds from all directions or a specific direction depending on its technical built. This sensitity to sound from one or more directions is called Directionality. Based on this property, there are 3 main types of microphones available in the market -
Omnidirectional Microphones
Directional or Unidirectional Microphones
Bidirectional Microphones
Omnidirectional Microphones
These microphones pick up sounds from all directions and are generally not recommended for recording speech. That said, they’re a reasonably good choice when recording the voices of a large number of people together – such as a conference where several people are seated around a table.
Because of the simplicity of their design, omnidirectional microphones are considered more rugged and produce a more ‘natural’ sound recording (as compared to bidirectional/unidirectional microphones). They are also less sensitive to wind/pop noises, resulting in clearer recordings. The drawback is that because they record sounds from all directions, a lot of unwanted sounds such as shifting chairs, doors opening, side conversations, vehicles passing by, etc. can also get recorded.
When using an omnidirectional microphone in an indoors setting, it’s a good idea choose a quiet room and lay down some ground rules for the participants before beginning recording. When outdoors, the microphone should be placed as close to the speaker as possible.
Directional (aka Unidirectional) Microphones
These microphones pick up sounds from a single direction – though single is a relative term. There are 3 major categories of directional (or unidirectional) microphones -
Shotgun Microphones
These come in two varieties – the long shotgun and the short shotgun microphone. These microphones are best for outdoor recordings because they have a very narrow ‘angle of acceptance’ or ‘pickup pattern’ or simply put, the area from which they pick up sound. This means they can pick up the particular sound they’re directly towards and reject all other surrounding noise to produce a very clear recording.
Long shotgun microphones provide the highest level of directionality and pick up sound from only the person/object that they’re pointed at. This leads to a very high quality of recording and makes them ideal for noisy locations. The downside of using these microphones is that since they’re very long (and often used with a boom), they normally need a second person to operate. Also, the microphone must consistently be pointed directly towards the speaker – any movement away from the speaker will result in an interruption of the flow of sound to the microphone and thereby impact the recording.
Short shotgun microphones are, well, shorter. Their properties are similar to the long shotgun microphones, the only difference lying in the slightly wider ‘angle of acceptance’ of the short shotgun. They are more portable as well; this makes them the microphones of choice for outdoor recordings that require a degree of mobility – such as interviews conducted on the street.
The high level of directionality of shotgun microphones is especially useful when the subject is not close to the microphone. The more the distance between the speaker and the microphone, the more directional the microphone needs to be.
Cardioid Microphones
Cardioid microphones are the ones most commonly used for speech recording. That’s because they are directional like the shotgun microphones yet offer flexibility in terms of the ‘angle of acceptance’ as well as size and portability. They come in 3 varities – cardioid, hypercardioid, and supercardioid.
Cardioid microphones are considered best for recordings that involve a large number of speaker (as long as they’re seated within the pickup range and direction of the microphone). They pick up sound mainly from the direction that they’re pointed in, some from the far sides of the microphone, and very little from behind the microphone. Since they’re unidirectional, they eliminate a lot of surrounding noise and produce high quality recordings.
Hypercardioid microphones are a step higher than the cardioids in terms of directionality. They have a narrower angle of acceptance and are very effective in eliminating noise from the rear of the microphone. The Supercardioid microphones on the other hand, eliminate more of the sounds from the sides of the microphone than from the rear.
The hypercardioid and the supercardioid microphones offer a high level of directionality (though lesser than the shotgun microphones) along with portability. Also, they don’t need to be pointed directly towards the speaker and therefore offer more flexibility of movement both for the microphone and the speaker.
Bidirectional Microphones
As the name suggests, these microphones pick up sounds from two opposite directions and reject sound from other sides. Also known as figure-of-eight microphones, these microphones are useful for recording two-person interviews where two people are seated on the opposite sides of a table. Bidirectional microphones are not very commonly used because of their limited application.
Some microphones come with multiple options that allow users to switch from let’s say cardioid to omnidirectional mode when required.
Frequency response
This property relates to the accuracy with which a microphone reproduces a range of sound frequencies. For example, a frequency reponse of 50-14Khz +/-3db indicates that the microphone covers frequencies between 50-14,000hz with a variation in volume not exceeding 3 decibles.
A microphone with a poor response to high frequencies will produce dull sounds while one with a poor response to low frequencies will sound tinny. In an ideal world, microphones would have a flat frequency response, i.e., the sound output will be exactly the same as the original sound input. However, this is never the case because no microphone is perfectly flat. A variation of +/-3db is common.
Impedence
Every circuit offers some level of resistance to alternating current (or audio signals) know as impedence. The lower the impedence of a microphone the better the quality of the recording. Most microphones are low-impedence, but when reading a spec sheet, here’s the general description to go by -
Less than 600Ω – Low impedence
600Ω – 10,000Ω – Medium impedence
Greater than 10,000Ω – High impedence
High impedence microphones are cheaper but their audio quality over long distance is not so great – leading to loss of high frequencies over long cables. Low impedence microphones are generally considered better.
Okay, so that was about the basic properties of a microphone. While this post is not exhaustive, it should make it easier for you to read a ‘spec sheet’ when you go out to buy a microphone. In the next post, we’ll cover some common types of microphones.
In the meanwhile, happy recording!

Are you planning to record an interview, lecture, teleseminar, conference, or some other event involving speech?  It’s been said that a recording can only be as good as the microphone that’s used – and the statement is absolutely true. Choosing the right microphone is as crucial as choosing the right recording device.

The choice of microphone for a recording depends on several factors such as location (indoors/outdoors), number of speakers, distance of the microphone from the speaker/s, etc. In this post we’ll look at some key properties of a microphone that should be considered before making a purchase.

Diaphragms

Every microphone has diaphragm i.e. a thin membrane of plastic, aluminium, or paper located in the head of the microphone that vibrates when hit by sound waves. Vibration of the diaphragm leads to movement in other parts of the microphone that generate electrical signals (or audio signals) that can be recorded. We’ll discuss the ‘other parts’ and their movement in a minute. There are 3 types of diaphragms – large, medium, and small – that differ in diameter.

Large diaphragms have diameters ranging from 3/4 inch upto to 1 inch and sometimes more. Their large surface area and comparitively flexible surface makes them more sensitive to sound. Because of their construct, they also have lesser ‘self-noise’ i.e. noise added to the recording by the microphone’s internal sounds. But while the general sound quality is quite decent, they don’t capture higher frequencies very well.

Small diaphragms (with diameters 5/8 inch or less) are lighter and therefore more responsive to higher frequencies. When sound waves strike a diaphragm from the side, they take time to travel across it’s body. If the diaphragm is large, the time taken to travel across will be longer and may result in loss of vibrations leading to reduced quality. That’s why large diaphragms work best when the sound waves strike from directly in front rather than the sides. With small diaphragms the loss of vibrations is negligible and therefore the sound quality is sharper no matter which direction the sound is coming from.

Transducers

A transducer is a device that converts one form of energy to another. Technically speaking, microphones are transducers that convert accoustic energy (sound waves) to electrical energy. Based on the kind of transducer used, there are 4main types of microphones available – Dynamic, Condenser, Ribbon, and Crystal. Dynamic and Condenser are the most widely used.

  • Dynamic Microphones

These simple, rugged microphones work on the principle of electromagnetism. When sound waves hit the the diaphragm of a dynamic microphone, the vibration makes a coil of wire (or a ribbon of metallic foil) move back and forth against a fixed magnet. This creates electric current or audio signals that can be recorded.

Dynamic microphones are simply constructed and sturdy. They don’t require an external battery or other power source to operate and compartively less expensive. They can handle high sound pressure levels without distortion but can’t capture high frequencies very well due to their mechanical construct. Ideal for rough use in live performances and on location recordings.

  • Condenser Microphones

These sensitive microphones work on the principle of capacitance (the ability of a body to hold electrical charge). Condenser (aka capacitor) microphones consist of two plates formed by a thin conductive diaphragm and a metallic back plate – these together form a capacitor. A fixed charge is placed across this capacitor through an external power source such as a battery or a phantom power supply. When the diaphragm vibrates under the force of sound waves, there are fluctuations in the capacitance leading to changes in voltage between the plates (voltage being inversely propotional to capacitance and capacitance being inversely proportional to the distance between the plates). These changes in voltage can then be recorded.

Condenser microphones are sensitive to a wider range of frequencies and can pick up softer sounds. They also have a flatter frequency response. The downside is that they are fragile and therefore unsuitable for rough use. They are also quite expensive. Best for in studio or home recordings.

Directionality

A microphone can pick up sounds from all directions or a specific direction depending on its technical built. This sensitity to sound from one or more directions is called Directionality. Based on this property, there are 3 main types of microphones available in the market -

Omnidirectional Microphones

Directional or Unidirectional Microphones

Bidirectional Microphones

  • Omnidirectional Microphones

These microphones pick up sounds from all directions and are generally not recommended for recording speech. That said, they’re a reasonably good choice when recording the voices of a large number of people together – such as a conference where several people are seated around a table.

Because of the simplicity of their design, omnidirectional microphones are considered more rugged and produce a more ‘natural’ sound recording (as compared to bidirectional/unidirectional microphones). They are also less sensitive to wind/pop noises, resulting in clearer recordings. The drawback is that because they record sounds from all directions, a lot of unwanted sounds such as shifting chairs, doors opening, side conversations, vehicles passing by, etc. can also get recorded.

When using an omnidirectional microphone in an indoors setting, it’s a good idea choose a quiet room and lay down some ground rules for the participants before beginning recording. When outdoors, the microphone should be placed as close to the speaker as possible.

  • Directional (aka Unidirectional) Microphones

These microphones pick up sounds from a single direction – though single is a relative term. There are 3 major categories of directional (or unidirectional) microphones -

  • Shotgun Microphones

These come in two varieties – the long shotgun and the short shotgun microphone. These microphones are best for outdoor recordings because they have a very narrow ‘angle of acceptance’ or ‘pickup pattern’ or simply put, the area from which they pick up sound. This means they can pick up the particular sound they’re directly towards and reject all other surrounding noise to produce a very clear recording.

Long shotgun microphones provide the highest level of directionality and pick up sound from only the person/object that they’re pointed at. This leads to a very high quality of recording and makes them ideal for noisy locations. The downside of using these microphones is that since they’re very long (and often used with a boom), they normally need a second person to operate. Also, the microphone must consistently be pointed directly towards the speaker – any movement away from the speaker will result in an interruption of the flow of sound to the microphone and thereby impact the recording.

Short shotgun microphones are, well, shorter. Their properties are similar to the long shotgun microphones, the only difference lying in the slightly wider ‘angle of acceptance’ of the short shotgun. They are more portable as well; this makes them the microphones of choice for outdoor recordings that require a degree of mobility – such as interviews conducted on the street.

The high level of directionality of shotgun microphones is especially useful when the subject is not close to the microphone. The more the distance between the speaker and the microphone, the more directional the microphone needs to be.

  • Cardioid Microphones

Cardioid microphones are the ones most commonly used for speech recording. That’s because they are directional like the shotgun microphones yet offer flexibility in terms of the ‘angle of acceptance’ as well as size and portability. They come in 3 varities – cardioid, hypercardioid, and supercardioid.

Cardioid microphones are considered best for recordings that involve a large number of speaker (as long as they’re seated within the pickup range and direction of the microphone). They pick up sound mainly from the direction that they’re pointed in, some from the far sides of the microphone, and very little from behind the microphone. Since they’re unidirectional, they eliminate a lot of surrounding noise and produce high quality recordings.

Hypercardioid microphones are a step higher than the cardioids in terms of directionality. They have a narrower angle of acceptance and are very effective in eliminating noise from the rear of the microphone. The Supercardioid microphones on the other hand, eliminate more of the sounds from the sides of the microphone than from the rear.

The hypercardioid and the supercardioid microphones offer a high level of directionality (though lesser than the shotgun microphones) along with portability. Also, they don’t need to be pointed directly towards the speaker and therefore offer more flexibility of movement both for the microphone and the speaker.

  • Bidirectional Microphones

As the name suggests, these microphones pick up sounds from two opposite directions and reject sound from other sides. Also known as figure-of-eight microphones, these microphones are useful for recording two-person interviews where two people are seated on the opposite sides of a table. Bidirectional microphones are not very commonly used because of their limited application.

Some microphones come with multiple options that allow users to switch from let’s say cardioid to omnidirectional mode when required.

Frequency response

This property relates to the accuracy with which a microphone reproduces a range of sound frequencies. For example, a frequency reponse of 50-14Khz +/-3db indicates that the microphone covers frequencies between 50-14,000hz with a variation in volume not exceeding 3 decibles.

A microphone with a poor response to high frequencies will produce dull sounds while one with a poor response to low frequencies will sound tinny. In an ideal world, microphones would have a flat frequency response, i.e., the sound output will be exactly the same as the original sound input. However, this is never the case because no microphone is perfectly flat. A variation of +/-3db is common.

Impedence

Every circuit offers some level of resistance to alternating current (or audio signals) know as impedence. The lower the impedence of a microphone the better the quality of the recording. Most microphones are low-impedence, but when reading a spec sheet, here’s the general description to go by -

Less than 600Ω – Low impedence

600Ω – 10,000Ω – Medium impedence

Greater than 10,000Ω – High impedence

High impedence microphones are cheaper but their audio quality over long distance is not so great – leading to loss of high frequencies over long cables. Low impedence microphones are generally considered better.

Okay, so that was about the basic properties of a microphone. While this post is not exhaustive, it should make it easier for you to read a ‘spec sheet’ when you go out to buy a microphone. In the next post, we’ll cover some common types of microphones.

In the meanwhile, happy recording!

How To Choose A Digital Voice Recorder

Written by admin on September 29, 2009 - 4 Comments

If you’re a student or business person who needs to record andprocessaudio files often, you probably know how important it is to choose the right recording device.

Digital Voice Recorders (DVRs) are a great way to create high quality audio files that can easily be transferred to a computer later for editing, customization.

There are a huge number of choices available in the DVR market. So knowing what to look for is important. Here are some basic features to consider when shopping for one:

Sound Quality

Most DVRs come with multiple sound quality settings, for e.g. LP (Long Play – lowest quality), SP (Standard Play – medium quality), and HQ (High Quality – highest quality). Higher levels of quality require more memory and consequently reduce recording time.

If you’re recording the audio for your own listening then even the lowest level of recording may be sufficient (may be). However, if you plan to use the recording to create products (like podcasts or CDs) it would be wise to choose the highest level of recording and supplement recording time with additional storage devices like flash drives and removable memory cards.

Microphones

Built-in microphones in most DVRs make them completely self-contained recording units. On the flip side though, they capture all sounds indiscriminately – including the sound made by the recorder itself – so they’re great for single-speaker audio recorded in a quiet room but not so effective if there’s any amount of noise around or if there are multiple speakers involved. They also limit one’s options in terms of positioning the microphone according to the kind of audio being recorded (for e.g. if you’re interviewing someone, you’d have to keep moving the recorder between the two speakers – and every time you do that, the noise from the movement will be recorded).

Choosing a DVR with an external microphone jack is by far the best option. You can then attach a lavalier, unidirectional, or omnidirectional microphone to the device according to the type of audio you plan to record.

Telephone Adapter

Some DVRs come with a telephone adapter that can be used to record telephonic interviews, teleclasses, etc. External phone adapters are also available.

PC Connectivity

If you want to work on your audio files using a computer (for creating information products, editing content, etc.), your DVR must have a USB port and connectivity cable that will allow you to transfer audio files from the recorder to your computer.

File Formats

If you plan to share your audio files with others, it’s important to save them in a format that can be easily played. The four most common file formats are DSS (Digital Speech Standard), WMA (Windows Media Audio), WAV (Waveform), and MP3 (MPEG-1 Audio Layer 3). DSS files require additional software to play on PCs, WMA files are compressed files that can be played on the Windows Media Player, WAV files are high-quality, uncompressed files that are very large, and MP3 files are compressed files that are much smaller than WAV but almost the same quality.

Some recorders create files in proprietary formats that can only be played on the device or using its companion software. If you choose one of those, it’s advisable to either convert the files to one of the common formats before sharing them with others OR send the companion software along with the file.

Recording Time

This varies from product to product. Recorders can store anything from 90 minutes to 20 hours of recording. External storage devices such as flash drives and memory cards are also available.

Recording time is directly related to the level of quality chosen. High quality audio takes up more space and reduces recording time. With a low quality setting your device can record more. You should choose a device that is suited to the kind of audio you want to record.

Battery life

The battery life of a DVR can be anything between 25 hours to 32 hours (this can however vary depending on how old the batteries are, when they were last used, etc.). It’s advisable to choose a device with both battery and electrical adapter capacities.

There are many other features of DVRs that can be considered at the time of purchase, but these are the main things to look for.

And for the visual learners amongst you, here’s a great video guide to portable digital voice recorders from B&H – http://www.youtube.com/watch?v=8Ey_ySC9aO0

Happy recording!

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