Date: Mon, 17 Feb 2003 15:59:39 -0700

Author: Jerry DiMarco

Subject: Re: Question about interference of sound waves


One point not mentioned - reflecting surfaces near the speakers will
obscure the effect. For instance, if the speakers are sitting in the
middle of a table, sound reflecting off the table top will make the
speakers less of a point source. Putting them at the front edge of the
table eliminates this problem...


At 02:40 PM2/14/2003, you wrote:
>Can anyone recall the criteria for the angle at which destructive
>interference occurs for a sound wave of wavelength (lambda) emitted from
>two speakers separated by a distance d?
>I'm trying to set up this demo in a lecture hall, and it doesn't seem to
>work well, so I'm thinking that I may be making an incorrect assumption
>about the physics.
>Can anyone suggest a wavelength/separation combination that works well?
>Scott Shelley
>Haverford College


Jerry DiMarco
Manager of Lecture Demonstrations and Instructional Labs
Montana State Univ., Physics Dept.
Bozeman, MT

Our Motto: "We don't use anything the way it was meant to be used."
From Mon Feb 17 18:07:22 2003
Message-ID: <>
Date: Mon, 17 Feb 2003 18:08:37 EST
Subject: Re: cellophane tape
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
X-Mailer: AOL 5.0 for Mac sub 9
X-MailScanner: Found to be clean
X-MailScanner-SpamCheck: not spam, SpamAssassin (score=1.9, required 10,
X-MailScanner-SpamScore: s
X-Listprocessor-Version: 8.2.09/990901/11:28 -- ListProc(tm) by CREN

I don't know if anyone has suggested this, but regular cellophane packing
tape, available at Staples is birefringent and works well.
Karen Bouffard
From Mon Feb 17 18:25:30 2003