Audio Bit Depth and Sample Rate

August 9, 2017 by Ben Stowe, CTS

In today’s world, nearly all audio is digital at some point between it’s capture, reproduction and amplification. There are terms that are often tossed around, but seldom understood. Bit Depth and Sample Rate are two such terms, and both are fairly self-explanatory when we break them down.

Sample Rate determines how often a digital slice is taken of an analog signal. A higher sample rate means more slices are taken per second. The Nyquist theorem states that the sample rate should be twice that of the highest produced frequency. The human hearing range is approximated at 20 Hertz (Hz) to 20,000 Hz, therefore, a sampling rate of at least 40,000 Hz would be necessary. CDs, and subsequently MP3s have a sampling rate of 44,100 Hz as defined by the Red Book standard. In the professional audio realm most devices are 48,000 or 96,000 Hz. Those are typical values for digital audio transports as well, such as MADI or Dante.

Bit Depth is a measure of how “deep” each slice of data is. As the illustration shows, the more “boxes” in that slice, the more accurate the reproduced sound is going to be to the original analog audio. This is due to the amount of dynamic range afforded by the bid depth. A CD has a bit depth of 16, which allows for approximately 90 dB of dynamic range, whereas the MADI digital audio transport allows for up to 24 bits and Dante now offers up to 32 bit. The greater the dynamic range, the greater the signal to noise ratio is going to be.

The short summary here is that the higher each number is, the higher the quality the audio is going to be. However, bear in mind a chain is only as weak as it’s weakest link. The quality of the signal will be limited to the lowest values at any point in the audio signal chain. There’s also a point of diminishing returns. It’s very unlikely anyone will be able to identify an audible difference between 48k and 96k or 24 bit and 32 bit on a DJ system.

(Illustrations courtesy of Audinate)

Ben Stowe, CTS Ben Stowe, CTS (17 Posts)

Ben’s love of electronics and technology led to years of schooling in Electricity, Electronics, Robotics and Lasers. Ben supported himself through school by building and selling strobe lights and other electronic devices. He built his first DJ show largely from scratch and scrap, often repairing broken items others had thrown away because he could not afford to buy new equipment. He holds a Minnesota electrical license, and his AV installs have been featured in almost every major industry trade magazine. His relentless passion for education has led to a number of other certifications and accreditations, including the most widely recognized one in the AV industry, the InfoComm CTS. His love for education inspired him to begin the ProAcademy educational sessions, focused on increasing understanding of AV technologies within the industry. Ben has been involved in a number of technical writings, lectures, presentations, as well as research and development assistance with a number of manufacturers for products, industry wide. He is also a regular contributing author to industry magazines in the United States and Europe. Ben’s presentations have been featured across the world both as a part of industry leading trade shows, and as a presenter for various groups and functions. Some of these events include BPM in the United Kingdom, Mobile Beat, the ADJA National Convention, Wedding MBA, and a national tour as a headlining presenter for an industry magazine. The United States Armed Forces branches have also called upon Ben to provide engineering and training assistance. His highly informational, slightly nerdy and always funny presentation style have made him a favorite at events, while his sincere desire to help people with their application of technology have made him a favorite with them after the event. Ben serves the industry as the President of NLFX Professional, an industry leading supplier of sound, lighting and video systems, a role he has maintained since founding the company in 1993.

Filed Under: Sound