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I was at a concert yesterday and noticed that the lead guitar seemed quite quiet. My friend who was next to me also agreed with me, however other friends seemed to have no issues. My first thought would be somehow there was destructive interference, and stumbled across this question. I wonder, though, could destructive interference happen at a concert venue? One with tens or hundreds of speakers? Also if it was destructive interference, wouldn't it affect all of the instruments?

From Alex Feinman's answer he mentions dead spots, but I am not sure if that means that most of the sound would be cancelled out.

In a well-prepared concert hall, the space itself is constructed in a way to provide multiple bounces for the sound to arrive at every audience member. This is on purpose, to reduce the occurrence of destructive interference. Some halls have well-known "dead spots" where performers cannot be heard, or where audience members cannot hear; modern acoustic theory uses diffusers to avoid this.

This was at the Columbus Pavilion and we were standing just right of the set of left speakers (blue arrow)

Columbus Pavilion Image Image credit Brock Bradley

For a better aerial view, here is the position in Google Maps.

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If the lead guitar was playing a single note and that note was a pure sine wave and the sound from the guitar was reaching you from two different directions (e.g. the direct sound and an echo) then you could get a stable interference pattern.

In practice the sound will be echoing off everything in the hall so you won't get an interference pattern, and even if you did that pattern would shift every time the guitar played a different note. So no, the guitar can't sound quiet due to destructive interference.

However reflection of sound can cause focusing so the sound intensity can different in different areas, though concert halls are normally designed to minimise this effect. If there really was a difference in the sound intensities at you and your friend's positions maybe this was the cause.

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  • $\begingroup$ I updated the question with more information about the venue. I'm sure it was designed with sound reflection in mind, but it is quite open. We were also right in front of speakers. Given we were right in front of the speakers, and the unlikeliness of destructive interference should I assume the guitar was just low? $\endgroup$ – Sven Writes Code Sep 13 '17 at 14:37

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