Backgrounds to audio
- What is music?
- Technical explanation
- Music and technique
- Music and human hearing
- Conditions to technique and environment
- Technicals terms
What is music?
Music is emotion. Shorter and better it can't be described.
You can enjoy music or it can make you happy, you can relax on it, find it irritating, or can change your mood.
With music you can become awake, you can fall asleep, and it is frequently present in private or at work.
We have preferences in music, we (dis)approve music, we make choices in music, but also make choices for music.
In short: it controls our life and (re)calls emotions.
We can describe music also in a 'technical' manner, then it is a combination of certain
sounds with
rhythm
and
loudness
.
Technical explanation
The separate sounds in music can be reduced to frequencies. A certain frequency means a specific number of soundwaves per second. These soundwaves move themselves as tiny waves of pressure in the air. Because it has been put earlier that music is built from several consonances and tones, this implies that these pressure waves also have different frequencies.
The human hering observes these tiny pressure waves by means of the ear and puts this into electric pivots for the brain. By means of the brain we observe the sounds and music.
Music and technique
Unfortunately (is it?) we generally hear music by means of technical resources, like loudspeakers or headphohes. Let's assume that a technical means is a loudspeaker.
With respect to a live concert a perfect reproduction isn't possible. This is mainly because of each apparatus has its own deviation and error margins, how small though.
How well a technical solution is, perfect reproduction of a live concert is therefore not possible. One must be noticed, however, that with the current state of technique the differences have become this way small or can become such a quality that for the average auditor it is largely sufficient.
When (re)producing music, mainly the technical properties and performance are important, they can be measured and proven right.
When human interpretations and influences become a significant part, it often goes wrong. The different opinions and preferences ensure that never an univocal definition will come concerning music and how it must be processed technically.
It has been occurred that a technical good system commercially failed because it
would sound not well. The real reason was that the system was to good, one had other preferences and ideas about a good system.
Music and human hearing
The human hearing can not observe infinitely sounds. The frequency span have been limited, there is an hearing threshold and the hearing itself (brains) is sensitive to masking.
To start with frequency: it is widely accepted that absolute hearing goes from 20 to 20kHz, this is basically correct. But to be entirely complete: people can observe frequencies (!) as from approx. 10Hz (noticeable as ultrasounds in the body) up to possible 40k à 50kHz [note 1]. I have done a test where this effect can be "noticed" [note 2]. Concerning litteral hearing, the frequency span is from approximately 20Hz up to 20kHz.
Also there is an hearing threshold, complete gentle sounds are not perceptible. The hearing threshold is frequency dependent. In the speech area (approx. 300 up to 4500Hz) the human hearing is the most sensitive.
The hearing is also sensitive for masking effects. This means among other things that when 2 tones sound and 1 is very loud, the other tone is not or hardly heard.
These three mentioned effects (there are a few more) result in a hard to understand behaviour of the human hearing.
Conditions to technique and environment
Putting conditions to technique and the listening environment is a way to get a pure and clean reproduction.
Also in this case the weakest chain stipulates the total quality. This applies to the complete chain of recording, reproduction via a mc/lp/cd/dvd player, (pre)amplifier and the loudspeakers. All these must be of course of good quality.
Generally the loudspreakers and there position in the room are the weakest links in the musical chain. Moreover the quality of some recordings is not to well, like distortion and clipping. In this cases it's clearly understandable that a good result (=reproduction) can never been reached.
Summarised it means that mainly the technique ascertains whether the reproduction sounds acceptably. Technically spoken, it is annoying is that some people will impose there personal preferences to technique. Whereas this not always an improvement is in qualitative way.
Example: many commercial guys pick one component out of the musical chain and sell it (with an associated price!) as if with this component the complete chain becomes suddenly perfect. I think that it needs no further explaination why this is absolutely insufficient...
Technicals terms
- The frequency of a tone is equal to the number of soundwaves per second.
- Sound moves as
pressure waves in the air; but no air is moved.
- One can say that music is built from a (finite) range of frequencies.
Still having questions?
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[1]: It is scientific (more or less) proven that high (ultrasonic) sounds are perceptible in combination with lower tones; the influences run of virtually nothing to perceptible with selected signals. At this moment I try to retrieve sources which confirms this and what kind of signals are used. Any help is welcome...
Also listening tests with SACD give as result that hearing do exist above 20kHz, but it is marginal. An English study has been done by the ' Institute of sound and Vibration Research ' (available at HSE Books) that confirmed that ultrasonic tones influence the hearing up to and including hearing damage, also the (dutch) TNO and ARBO had done studies to the detrimental impact of high frequencies. Conclusions are that high frequencies can influence the human perception, but all details are (still) not completely proved scientifically.
[2]: Connect a fuction generator to a good quality headphone, set in to e.g. 7kHz (be carefull about the volume!) and listen to the difference between a block- and a sine wave. Repeat this test with increasing frequency and determine the frequency where no more audible difference can be noticed between the block- and a sine wave.
This last frequency multiplied by 3 (thirth harmonic because of block wave) gives the highest audible frequency. Note: younger ears can hear better!
