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Corvaldt's picture
Last seen: 3 years 4 months ago
Joined: Nov 1 2017 - 1:23pm
Hunt the Frequency Gobbler! Tips needed.

So I have been doing some room measurements. I have seen that there is a big old dip at 1.454khz and then the first two harmonics (2.91khz, 4.36khz) before a big peak at the 3rd harmonic (5.816khz). This pattern (3 dips and then a big peak) at the successive harmonics of 1.454khz up until past 20khz.

My guess is that there something in my room screwing things. I am very new to room acoustics. Does anyone have any ideas how one goes about investigating these things properly? I find it really irritating not knowing what is going on!


absolutepitch's picture
Last seen: 1 week 1 day ago
Joined: Jul 9 2006 - 8:58pm
room effect

What are the dimensions of the room? How are you getting the dips, with the SPL meter in free space away from boundaries and far from the speakers?

Just to avoid confusion later, a wave at a fundamental frequency is also called the 1st harmonic. The next harmonic (2nd) is a doubling of the frequency of the fundamental, and is called the 1st overtone.

Usually, peaks and dips in a room are more easily heard in the bass range, with room effects dominating at frequencies less than 500 Hz or so. At the frequency of your fundamental of 1.454 kHz, the wavelength is about 15 inches, with the first half-wavelength boundaries at about 8 inches. You may need to describe you room, system setup locations and where you are measuring these dips, and how deep are the dips in dB you are talking about.

Kal Rubinson
Kal Rubinson's picture
Last seen: 1 hour 35 min ago
Joined: Sep 1 2005 - 9:34am
Interference (peaks and nulls

Interference (peaks and nulls) at those frequencies suggest looking at Speaker Boundary Interference Response (SBIR). Might only take some speaker repositioning or a relationship to a wall to fix.

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