Audio Solutions Question of the Week: What is High-Resolution Audio?

Question: What is High-Resolution Audio?

Answer: The audio world is buzzing (forgive the pun) over High-Resolution Audio. Is this just the latest fad in the industry or is there really something to it? Before answering this question, let’s have a brief review of digital audio from the 10,000-foot level. In the very late 1970s and early 1980s, digital recording and playback systems began to emerge. Before this time, audio was distributed on physical medium, such as a vinyl record or a cassette tape. But with digital, audio exists as a file. To produce a digital file, an analog-to-digital convertor (ADC) takes samples of the audio stream at a certain rate, most commonly 44,100 times per second. This is referred to as the “sample rate.” The amount of information captured in each sample is referred to as the “bit depth,” and most commonly is 16 bits. 44,100 Hz, 16-bit is considered “CD-quality” audio.

In order to listen to the audio that is stored within a digital file, the process is reversed. A digital-to-analog convertor (DAC) is used to convert the audio back to an analog signal that can be listened to with a loudspeaker or headphones.

These two factors – sample rate and bit depth – determine the quality of a digital recording. Storage and transmission of digital audio files have always been of concern, particularly in the early days when storage and transmission bandwidth was either limited or expensive. To reduce the size of these audio files certain types of compression, such as that found on MP3 files, are used at great detriment to the quality of the audio. CDs and MP3s have been more or less the standard for listening to digital music for quite some time.

Technology has exploded in the last few years, and with lossless audio file formats, faster internet speeds, and storage space increasingly easy to come by (and in ever-smaller packages), the push is on to create audio equipment capable of capturing and reproducing much better and more accurate audio. Thus, Hi-Res Audio. True Hi-Res Audio is generally considered to be 96 kHz/24-bit or better. The Hi-Res Audio logo on products certifies that a product meets the Hi-Res Audio standards. Per these standards, headphones must have transducer frequency performance to at least 40 kHz.

Now the big question. By using Hi-Res Audio headphones will all music that you listen to be Hi-Resolution Audio? In other words, if you listen to an MP3 audio file using Hi-Res Audio headphones will the audio be High-Resolution? The answer is no. The audio file must have been recorded at a sample rate of 96 KHz or better and at a bit depth of at least 24-bit, and your music player must have the ability to play Hi-Res Audio files.

While on the subject of Hi-Res Audio headphones, we should point out that Audio-Technica has several headphones that proudly bear the Hi-Res Audio logo. Among these are the award-winning ATH-MSR7GM and ATH-DSR9BT.

If you have additional questions or would like a recommendation for an Audio-Technica product, feel free to contact the Audio-Technica Audio Solutions Department. We are always happy to help.


One Comment

  1. Many arguments over high-res audio ‘hype’ or ‘scams’ seem to ignore the larger picture of the inevitable inconsistencies within our current, disjointed transition period. It seems that we are in a phase of clunky transition, with partial hi-res implementation ‘bolt-on’s’ being applied to a standard-res framework.

    The issue seems much more expansive, especially when seen in context; as isolated developments in an eventually integrated high-resolution audio paradigm – a process which also leads to further refinements in our conventional understanding of auditory perception (and vice-versa).

    Our current understanding of sound and hearing is built upon a conceptual framework of discrete sine waves (the acoustic representation of a rudimentary trigonometric function). So, when conventional knowledge states that the range of human auditory perception is generally limited to 20 Hz – 20 KHz, this refers to testing based on the perception of measurable sine waves (isolated, single frequency waveforms without harmonics). The influences of sonic and ultrasonic harmonic interactions in real world sounds are irrelevant to this paradigm. On the basis of this type of perceptual research, most audio equipment is designed with a frequency response that excludes all ultrasonic harmonics and any (indirectly audible) integrated interactions with (directly audible) harmonics.

    With the early development of ‘high-resolution’ sampling rates of 192 KHz and beyond, recognition of the upstream/downstream frequency-bandwidth limitations has been generally ignored.

    Presently, the potentials of high-resolution audio are implemented more in concept than content. The Nyquist frequency theorem dictates that a sampling rate of 192 KHz can accurately digitize acoustic frequencies up to 96 KHz, yet this theoretical capacity remains unimplemented when applied to incoming signals which are transduced at a frequency-bandwidth of less than 20 KHz (or an output transduced in standard-resolution speaker systems).

    The result of these upstream/downstream transduction limitations of current audio technology is that ‘hi-res’ sampling rates merely render the measurement of more samples per second of limited frequency-bandwidth (standard-resolution) signals.

    These standard-resolution ‘links’ in an emerging high-resolution ‘chain’ seem to be the basis of A/B testing results where audible differences between standard and high-resolution audio are seen/heard as negligible to nonexistent.

    One compelling acoustic example for me is the audible difference between the sound quality composite of a live gong player in comparison to a standard-resolution (44.1 KHz, 16-bit) recording of it.

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