Basement room question

[Olson_jr]

. For those of you who remember me, you might recall that I'm something of an acoustics geek so this space is the result of years of deep exploration throughout the small room acoustics rabbit hole.

- Michael

Michael,

I have been in several basement listening rooms this year that have had a drop in ceiling height between the speakers and the listening space.

The untreated drop (12" or 16") is for forced air ductwork, and in both rooms, it is parallel to the front face of the speakers and encased in drywall.

Have you ever encountered such a listening space? if so what would you recommend for treatment of this area, if anything?

Both rooms seemed to have a lack of focus, for lack of a better term, and in both the farther back in the room the better it sounded.

Others' experience and input would also be appreciated.

Happy Holidays and may all your listening be in a well-treated room.

 

[GuyK]

How far from the speakers is the ductwork soffit?

 

[Olson_jr]

How far from the speakers is the ductwork soffit?

It varies in the two rooms, in the one room I have spent more time in it is probably 8-10 feet horizontally.

 

[tomlinmgt]

Michael,

I have been in several basement listening rooms this year that have had a drop in ceiling height between the speakers and the listening space.

The untreated drop (12" or 16") is for forced air ductwork, and in both rooms, it is parallel to the front face of the speakers and encased in drywall.

Have you ever encountered such a listening space? if so what would you recommend for treatment of this area, if anything?

Both rooms seemed to have a lack of focus, for lack of a better term, and in both the farther back in the room the better it sounded.

Others' experience and input would also be appreciated.

Happy Holidays and may all your listening be in a well-treated room.

First, keep in mind that the fundamental objectives when optimizing a room's acoustic characteristics for recorded music playback are 1) minimize or eliminate early reflections at the listening spot by creating a reflection free zone and 2) reduce the reverberant characteristics of the room to achieve a favorable reverb/decay profile. Doing number one typically takes care of number two unless the room is large and highly reflective in which case more treatment will be required than what is needed to create a reflection free zone at the listening spot. This is before we get into addressing room modal behavior which targets the bass frequencies and typically requires considerably more effort and treatment devices to get under control, but we'll not go into that since it doesn't really address the issue you're inquiring about.

Without knowing the design of the speakers and their dispersion characteristics or exactly where the drop is located in relation to the location of the speakers and listening spot, I can only suggest that the drop be made "invisible" or acoustically inert to the sonic energy coming from the speakers...and broadband absorption is the tool for that. So I'd cover the horizontal surface/bottom of the drop with 2"-3" thick absorption panels to eliminate reflections from that surface...reflections that have a very high likelihood of being early reflections which need to be dealt with anyway to a achieve an (early) reflection free zone at the listening spot. It will also eliminate the interaction between the drop and the floor if the floor happens to be reflective.

There's a chance that the vertical surfaces of the drop are interracting with any opposing, hard and parallel surfaces to create an echo...which is not desirable but just how much it's affecting the fidelity of the music is impossible for me to estimate given the information you've provided.