Inquiry-Based Labs in Musical

Acoustics

M. S. Pettersen

Washington & Jefferson College

“Good Vibrations:” a course in musical acoustics for non-majors

Goal: bring active learning into a class for non-science majors

• Studies show active learning methods are more effective (Laws; McDermott; Redish and Steinberg; Birk and Foster; etc.). – Students see and hear phenomena for themselves.

• The best way to learn about science is to practice it– It’s fun, too!

… which implies that the course should:

• Include the old-fashioned kind of experiments that students can see, hear, feel

• Alternate bench-top experiments with measurements of real instruments, acoustics of campus auditoriums, etc.– Using Vernier Software’s Logger Pro– Using free software from the internet

• Incorporate music listening

Old-fashioned experiments

Siren disc Monochord (sonometer)

Melde’s apparatus Chladni plates

New-fangled experiments using Logger Pro

• Overtones

• Inharmonicity in the piano

• Percussion instruments and virtual pitch

• Differences among the woodwinds

• Sound envelope

• Echoes

• Auditorium acoustics

Inharmonicity of the piano

Percussion instruments; virtual pitch

Timpani Bass drum

Differences among the woodwinds

• Clarinet: odd overtones only (one end open, one end closed)

• Saxophone: particularly strong second harmonic

• Flute: almost pure fundamental

Auditorium acoustics

Reverberation time is about 1 s

New-fangled experiments using software; Electronic music

• Fourier synthesizer Java applet

• Spectrogram software

• Software synthesizer (electronic instruments)

• .mp3 compression with MediaMonkey

• Signal processing and sound editing with Audacity

Fourier synthesizer Java applet

http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=33

Spectrogram software

A. Aaaaaaaaaaa!

B. FFFFF

Note formants, overtones

Signal processing and sound editing with Audacity

Row, row, row your boat….

Listening

• Bach Brandenburg #2: overtones on the Baroque (valveless) trumpet

• Berlioz Requiem – Dies Irae (Tuba Mirum) – speed of sound

Sources

• Evolution eKeys Keyboards:

http://www.zzounds.com

• Auditory Demonstrations CD:

http://asa.aip.org/discs.html

• Fourier synthesizer Java applet:http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=33

• Spectrogram software:http://www.visualizationsoftware.com/gram.html

• Media Monkey audio format converter and .mp3 ripper:http://www.mediamonkey.com/download.htm

• Audacity sound editing and processing software:http://audacity.sourceforge.net