Sound Radiation Characteristics of a Rectangular Duct with Flexible Walls

Table 4

(a) Coupled modes of a rectangular duct. (b) Comparison of uncoupled and coupled modes of a rectangular duct.

(a)

Mode number	Frequency (Hz)	Mode number	Frequency (Hz)	Mode number	Frequency (Hz)
1	100.48	11	208.23	21	282.82
2	105.36	12	219.39	22	294.39
3	121.47	13	226.30	23	301.62
4	126.61	14	232.59	24	311.92
5	140.08	15	238.81	25	343.82
6	141.47	16	254.16	26	347.07
7	162.99	17	258.02	27	352.22
8	177.12	18	260.92	28	361.28
9	189.14	19	266.91	29	367.71
10	195.22	20	282.74	30	374.89

(b)

Uncoupled mode frequency (Hz)	Mode type	Coupled mode frequency (Hz)
99.22	Structural	100.48
113.3	Acoustic	105.36
114.59	Structural	121.47
127.08	Structural	126.61
140.51	Structural	140.08
141.94	Structural	141.47
163.47	Structural	162.99
177.17	Structural	177.12
189.68	Structural	189.14
195.60	Structural	195.22
208.72	Structural	208.23
224.69	Structural	219.39
226.6	Acoustic	226.30
345.1	Structural	343.82
345	Acoustic	347.07