Instrument demonstrations

DHC 161March 4, 2011

Violin family

440 Hz

220 Hz

110 Hz

violin octetSet of eight scaled violins designed by Carleen Hutchins

Luthier, scientist, and founder of the Catgut Acoustical Society

Violin construction

23”

14”

violin construction

corner blocks

sound post

bass bar

ribs

lining strips

neck

scroll

back platefingerboard

tuning pegs

bridge

violin bridge and soundposttransmitting the vibrations

Downward force of strings is about 20 lbs. Supported by sound post and bass bar.

bridge has a rocking motion

Violin response

from Bissinger, Rowe (2007)http://www.acoustics.org/press/153rd/bissinger.html from Hutchins (1981)

A0 is Helmholtz cavity mode (MAR)

A1 is longitudinal cavity mode

CBR, B1 are body modes (mostly top plate)

measurement of 1735 Guarneri del Gesu standing wave patterns

desirable for A0 and CBR to coincide with open strings (D and A)

the violaHistorically, the older instrument

Tuned perfect fifth lower than violin

but strings and body are not 3/2 (50%) larger!

Open string frequencies do not line up as well with air and body resonances.14” 16”

the cello

Tuned an octave below the viola

29.5”

C G D A

the bass violalso known as the “double bass”

Tuned in fourths: E A D G

(one octave lower than guitar)

C extension allows bassists to reach low C, one octave below the cello