Changing Bit Rate on Wav Files

Hi :slight_smile:

I have the latest version of Audacity 2.1.3 on Windows 7

And I have recorded some sound from a ZoomH4n Recorder in Wav Format, With the bit rate at 14111kps and on speaking with a sound engineer who hasn’t used Audacity for a while told me the best settings to retain the audio quality would be 48khz on 24bits if this makes sense?

So how would I be able to change the bit rate to 48khz which is CD quality please?

Many thanks

The term “bit-rate” is generally used for compressed audio formats, such as MP3, OGG, AAC and so on. The term is relevant here because compressed audio formats are designed to reduce the amount of data per second, and “bit-rate” is the measure of “how much data per second”.

For uncompressed formats, such as WAV and AIFF, the bit-rate (number of binary digits per second) can be calculated from the “sample rate”, “sample format” and “number of audio channels”,

“Sample Rate” is the number of audio samples per second. In Audacity, if you zoom in very close on a waveform you will see that the wiggly waveform is comprised of a sequence of dots - each of these dots represents an amplitude value at a specific point in time, and that is called a “sample”. The number of samples per second determines the upper frequency limit of the audio. Specifically, the maximum audio frequency that can be represented is half the sample rate. So a sample rate of 44100 Hz has an upper frequency limit of 22050 Hz. 44100 Hz (44.1 kHz) is the most commonly used audio sample rate, and is the standard for audio CDs. 48000 Hz (48 kHz) is also commonly used as it is the standard for DVDs. As a general guide, use 44100 Hz if your project is audio only, and use 48000 Hz if it is a video project.

“Sample Format” is the format of each individual sample. Typically this will be 8-bit (signed or unsigned), 16-bit integer (CD quality), 24-bit integer, 32-bit integer, or 32-bit float. Other formats are possible but not commonly used. The number of bits determines the number of amplitude levels that a sample may have. This in turn determines the digital noise floor. 8-bit audio is noticeably noisy and not suitable for good quality audio. For 16-bit audio, the noise floor is around -90 dB, which is likely to be better than the analog equipment that you are using. Top quality studio equipment may have lower noise than this, and so benefit from more bits per sample, so studio recordings are typically 24 or 32-bit. The default format in Audacity is 32-bit float, which is the recommended format.

The “bit-rate” for uncompressed audio is calculated as:
sample rate x sample format x number of channels
for example, for audio CDs, the sample rate is 44100 Hz, the sample format is 16 bit and the number of channel is 2 (stereo), so the bit-rate is:
44100 x 16 x 2 = 1411200 bits per second = 1411.2 kbps