Interesting Sound Slob

Stereo Recording Report

This report critiques six stereo recordings of a 30 second acoustic glockenspiel phrase, recorded in three different environments, using various microphone techniques. The purpose of the essay is to analyse the quality of the recordings, with regard to: frequency response, dynamics, stereo image and acoustic ambience. The paper will address the process I went about so as to best record the instrument, and the various factors that contributed different results, with reference to the overall sound of the chosen 'best track'. The recordings on the Minidisk are in order of perceived quality and for the purposes of this essay they will be referred to as 'Track 1' through 'Track 6'.

Due to the nature of the glockenspiel, it being a percussive instrument who's every key when struck 'rings' independent of other keys, one might suggest recording in a small, isolated studio booth would be best [see figure 1.0]. This is so as to capture: a clean, tight sound, with clear dynamics, also trying to preference the instruments 'true' sound, and not favour ambient sound created by acoustic environment. On Track 4 a 'close mic placement', one foot from the source, achieved the two latter goals. However, the sound is consequently flat and stuffy. Also, the mic is hand held and one can hear various extraneous 'pops' and undesirable noises. With regard to the frequency response, the proximity of mic placement allowed the mid-range 'body' to be clouded by upper harmonics, producing a dissonant 'ringing' sound. The stereo image is narrow, and flat as a consequence of poor mic placement.

It is then clear that glockenspiel benefit from larger acoustic environment and/or microphone placement being further from source. This would allow the 'ringing' upper harmonics to be less biting and allow them to contribute to a urethral quality when captured less directly in the reverberations of the acoustic environment. Track 2 is a good example of a more balanced natural timbre of the glockenspiel. The recording environment, that being a tiled rectangular bathroom [see figure 2.0], attributed: better tonal balance of instrument with regard to frequency response, dynamics and acoustic ambience. The reflective qualities in the surface of the environment [see figure 2.0] allows for a larger and longer reverberation, whilst the larger acoustic environment allowed for a fuller initial sustain and an extended decay time.

As seen in figure 2.0, Track 2 uses a distant mic placement of three feet from instrument - roughly equal to size of instrument (Huber & Runstein, 1995; p113), and roughly the same distance high, putting it close to the roof. Because of this, and the reverberation of the bathroom, the ringing top end frequencies are not over-accentuated by the microphone. However, a 'tinny' ambience is notable, possibly due to crispness of the reflections, and makes the room quite audible.

Furthering this, an even longer ambient trail and muddied, hollow tone can be heard in Track 3, also recorded in the bathroom with the microphone positioned from a further distance, random height and pointing into the corner [see figure 3.0]. Track 3 is a good example of the way poor mic positioning in relation to bad reflections allows for partial phase cancellation (Huber & Runstein, 1995; p114-115); hence the track sounds muddied and lacks definition. Also, one might hear some distortion when the dynamics of the piece get louder, even when it seemed like a relatively quiet track. This makes it clear that, although the acoustic ambience of the bathroom is full bodied, it is not very forgiving of large variance in amplitudes and frequency thus does not accurately represent a natural sound of the glockenspiel.

Tracks 1,5 and 6 recorded in the large room prove it to be the better of the three recording environments. The greater size of the room makes possible a better balance of ambient reverberation, preservation

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