Jens Jørgen Dammerud  

Stage Acoustics for Symphony Orchestras - Just Black Magic? Part II

Jens Jørgen Dammerud
September 6, 2019

Editor's Abstract (Click to Hide)

This article is the second of two that have come from Jens Jørgen Dammerud's PhD dissertation on Stage Acoustics —a subject not often addressed in acoustics books, but nonetheless quite important to performing musicians.

Contents of Part II

• Possible Consequences of the Acoustic Conditions Implied by the Orchestra
• Design of Stage Enclosures
• Overall Conclusions

- Ramon Ricker

HOW ACOUSTIC CONDITIONS AFFECT PERCEIVED CONDITIONS

Not much research has previously been carried out regarding which physical or acoustic factors control the ability to hear the other players clearly well balanced with sound from one’s own instrument. The most significant contributors to this subject are Jürgen Meyer and Anders Christian Gade and their research groups over the last four decades. This section focuses on how level and time differences may relate to perceived balance between instruments within the orchestra and conditions in general. Due to a lack of relevant scientific investigations it is only possible to draw up possible relations based on knowledge about masking effects, the precedence and the cocktail-party effect.

The subjective relevance of the within-orchestra sound levels and delays
If the delay of direct sound from different players is consistent the players appear to be able to adapt to the delay of sound from instruments across the stage. It appears likely that orchestral players are able to adapt to (more or less subconsciously) and not get rhythmically disturbed by delays of the direct sound within approximately 60 ms, which is the approximate maximum delay they will experience. This would imply that any sound events within 60 ms may be perceived as the ‘direct’ or the ‘immediate’ orchestra sound among the players. But the different delays from different instrument groups can contribute to perceptual temporal masking, where the sound from the instruments that arrives first contribute to make later arriving sound inaudible. Such an effect appears difficult to adapt to and overcome, since the masking effects origins much from the biological construction of our auditory system.

The significant level balance and time arrival differences between different instruments (Figures 4 and 5) appear to make it difficult for the players to hear all the other players clearly, well balanced with the sound from one’s own instrument. The string players can be expected to easily struggle to hear each other, since the mutual sound between string players can be perceptually masked by louder and/or more proximate instruments which are less delayed and attenuated. The sound from the instruments at the back will both arrive first and at a higher level and will easily mask the sound of other string players. Additionally, the percussion and brass players may struggle to hear the string players due to high direct sound levels from players within their own group or their own instrument.

These conditions of sound level and propagation delays are likely to make it difficult for the players to balance correctly. With significant attenuation or masking of sound at frequencies above 500 Hz, over-harmonic sound components from in particular strings are significantly reduced in level and the attack/transient sound of instruments are less audible. This is likely to also lead to intonation problems and acoustic timing cues being less audible. The intonation problems may be exaggerated by level differences between instruments on stage differing significantly compared to what the audience hears. This could be related to perceived pitch being affected by the actual sound level. If the sound of one’s own instrument is very loud relative to the others players, the player could potentially misjudge the pitch compared to what the audience hear when the over-harmonics of the sound is not clearly audible. The problem with mutual hearing

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