The Science of ... the Sound of Music

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The Science of ... the Sound of Music

A live performance plainly conveys the musicality and emotion of the music ... and so can an audio system.

The holy grail of audio reproduction for the music lover is the recreation of a live performance as it would sound were it played in front of you; that the sound of the music is coming from actual instruments and the singers rather than speakers. To achieve this feat you have to convince your brain with enough sensory detail to overcome the obvious suspension of disbelief.

For most people, and in most situations, a moderately priced desktop or bookshelf speaker system with a sub-woofer provides sufficient detail to be compelling - especially at normal or lower listening volumes. In these cases, the sound is considered 'hi-fi' and that is good enough to pass for high quality audio.  This system is what you listen to YouTube, Netflix and your music sources.  It sounds great ... and it is.  (BTW, we are talking about speakers, not headphones, in this article).

However, there is a domain beyond 'hi-fi' where, once experienced and appreciated, becomes a passionate pursuit of understanding the attainment of the magic.  This is the domain of the audiophile and its not about 100% audio signal simulation (as to fully and accurately duplicate the sound of an orchestra) ... its about understanding what it takes to have your brain fooled sufficiently to accept the magic of the illusion created before you. When you can discern live instruments and sense the emotion of the performance, then the audio system has done its job.

The Science of ... the Sound of Music

The Audiophile's description of sound requires that you must understand a few definitions:

  1. Tone.  A musical sound of definite pitch, consisting of several relatively simple constituents called partial tones, the lowest of which is called the fundamental tone and the others harmonics or overtones.  This is related to frequency.
  2. Timbre.  The quality of a musical note, sound, or tone that distinguishes different types of sound production, such as voices and musical instruments, string instruments, wind instruments, and percussion instruments.
  3. Energy (or SPL, Sound Pressure Level).  The local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a sound wave as measured using a microphone.  Human hearing ranges from zero ambient (the sound of a mosquito at 3m) to wall shuddering loudness and vibration.  SPL is both heard and felt.
  4. Transient response.  The ADSR (Attack/Decay/Sustain/Release) of a musical phrase. Consider this to be the accuracy of the system to follow a rapid or subtle change in either Tone, Timbre or Energy.  Of course, this is all about the timing accuracy of the system.

The Tone and Timbre of a sonic presentation immediately lets you identify the artist or instrument being played.  100% of audio gear today gets this right - and the level of fidelity of music is correlated with low distortion, low noise and accuracy in the frequency domain. Music is beautiful and completely listenable when the Tone and Timbre are good.

Music starts to become 'real' when you also sense Energy and Transients: sounding more like a live presentation rather than a recording.  Low frequency notes (such drum beats and the puffs of air from a singer's lips) create sound pressure which, however subtle, is felt by the listener.   Additionally, the first few moments of an instrument note or spoken word have tremendous influence on brain's ability to be convinced of the 'live-ness' of a presentation. When the timing accuracy of transients matches our mental record of live music reality we get transported to the live event.  Recent developments in audio technology have demonstrated that we have almost an unlimited sensitivity to transients.

Today, digital playback devices (even those in mobile devices) and desktop and bookshelf speakers (or earbuds or headphones) are all quite good.  So, even a purchase of a basic audio system delivers Tone, Timbre, Energy and Transients in sufficient quality to be regarded as 'Hi-Fi'.  A bit more money improves the sound and may become near-audiophile.

The ultimate in sound reproduction, however, does require a near quantum leap in both cost and component size and complexity - and likely the services of a professional audio consultant. AudioWise.ca (located in the Toronto GTA) has the passion and expertise to help you - and can be a good place to start.