By Marshall Chasin, AuD
The following post was first published in Back to Basics in The Hearing Review and appears here by permission of that publication.
Presumably the difference is that one has a volume control and the other does not. There are numerous acoustic engineering strategies that can control excessive volume levels of loud music and, for the most part, these are ignored in favor of allowing only recorded music. This decision is draconian (I have always wanted to use that word) and ignores the many approaches that would result in music enjoyment at an acceptable level. There are differences between live and recorded music and it is worthwhile to have a stroll down memory lane.
Recording of music began in 1878 with the Edison Phonograph, which was the single greatest step forward. In 1948 Columbia Records came out with the 12-inch 33-1/3 rpm record and 1949 saw the development of the inexpensive RCA Victor 7-inch 45 rpm record. In 1957 the Ampex 8 track recorder was invented and the Philips (and later Sony) compact disk in 1985. The MP3 format was introduced in 1990 (even though the portable MP3-player did not become available until 1998).
After the release of the Edison Phonograph people could finally listen to their favorite music in the comfort of their own living rooms (and I suppose horse-drawn carriages, but I would imagine that the bumpiness of the horse carriage and the inevitable intermittent sound prevented them from fully enjoying the music). Partly because the invention of the condenser microphone was still 40 years off (Wente, 1920), the Edison Phonograph had a very restrictive dynamic range. As a partial result, performance inventions such as violin “vibrato” had to be incorporated into the playing to ensure that the violin was heard above the harmony of the music and to replace some of the face-to-face contact that was lost in a recording.
With the advent of records- first the 78 rpm records and later the 33-1/3 rpm, and then the 45 rpm- the maximum volume was limited by the height of the grooves etched into the record. High-volume recordings were simply not possible because the playback needle would physically pop out of the groove. And high-powered amplifiers could not transduce high levels without some audible distortion.
The cassette form of media (1963) improved things in this respect, but all forms of media do have an internal noise floor- cassette noise is inherently broad band and can easily be heard during quiet portions and in between tracks. It was 13 years before Dolby came out with a noise reduction system in 1976 to minimize this audible tape noise. An entire generation of listeners grew up on hearing this tape noise and initially its absence was not liked. Early Dolby reviews were not stellar, but eventually Dolby helped to re-tune the listening ear. Dolby is a really neat system. Although it used filters, compressors, and amplifiers, the input spectrum was identical to the output spectrum, except that the (high-frequency) tape noise was removed. This could not be said of some other noise reduction systems of the time, since these tended to alter the shape of the frequency spectra, especially in the higher frequency region where tape noise was the most audible.
A major step back occurred in 1990 with the introduction of the MP3 audio format. I guess that I should say a “minor” step back occurred- just being overly dramatic! The MP3 format got rid of the tape noise (by getting rid of the tape), allowed distortion-free recording over a wider range of frequencies, and was not limited by the material of media (i.e., mylar and chromium oxide metal based tapes). But, it also introduced significant compression into the recordings.
Compression is used all of the time in hearing aids for hard-of-hearing people and on the surface sounds like a great innovation; this circuitry increases the output for soft sounds and reduces the output for overly loud sounds. Compression assures that the recorded music is within the dynamic range of the recording media. No longer are the softer elements of music inaudible, and no longer are the percussive crashes of cymbals beyond the capability of the MP3 player.
But, in doing these wonderful things, compression also alters the loudness dynamic cues that were intended by the performing musicians and composers. Music is “squished” into a dynamic range optimal for the MP3 media.
Today, this is one of the biggest complaints about modern .MP3 and other digital file formats. Radio stations have jumped on the bandwagon and even my favorite local jazz station “compresses the hell out of music”… a direct quote from a local musician.
I understand the need for compression with modern formats, but in some sense we were better off in the golden years of music recording (1976-1990). The recorded sound between 1976 (advent of Dolby) and 1990 (the period just before the MP3 format) were perhaps the closest we ever had to minimizing the difference between live music and recorded music.
Ease of volume control (recorded music) is one side of the noise regulation coin, but the other is a substandard level of music. Live music does not need to be compressed. Many of the things that a performing artist must do on a recording are arbitrary and a direct reflection of the inability to optimally transduce the recorded music. To enshroud a by-law or city noise ordinance in terms of live versus recorded music demonstrates a poor understanding of music and its effects.
