10. Acoustic Models of Sound Production
459
the resonance is higher. We also show profile for a flow rate of 251/s corresponding to a Q of 4. The shallower dive profile corresponding to a Q of
4 would indicate the whale called at an intensity less than it is capable
of because it did not use all the air in its lungs, assuming we have the
anatomical volumes correct. The variation in the depth of the blue whale
during calling is the major testable hypothesis of the proposed model.
8.2 A Dive Depth Limit?
A question related more to blue whale anatomy than to sound production
is. Can the blue whale avoid flooding the nasal passages when making deep
dives? If we assume a 2,000-1 lung volume and 200-1 laryngeal sac volume,
both these will be totally collapsed, and all the air will reside in the 100-1
nasal passage volume, at a depth of 220 m (see Eq. 7). Echo-sounder records
show blue whales diving to near 300m depth (Alling et aI.1991), so it seems
the whale must either flood the nasal passage, allow blood or tissue to fill
in the nasal passage, or hold a significant differential pressure. One approach
to estimating the minimum differential pressure a blue whale can hold is to
estimate the pressure associated with a blow. Using the rise time and rise
height to estimate flow velocity and treating the nasal passages as a nozzle
in a fluid dynamics calculation yields differential pressures of 1 to 2 bar, not
enough to allow diving 80m below the lung collapse depth (8 bar).
8.3 Gaps in Call Pattern Should Coincide with Surfacing
The presence of pauses between calls and breathing gaps is consistent with
the physical model presented here in that a type "B" call could not be produced without a depth change to compress or decompress the lung, thus
production of type "B" calls must cease while the whale is at the surface to
breath. The pressure required to compress the lung volume into the volume
on the narial side of the oscillating valve is too great to expect muscle contraction along to provide, thus requiring the depth-related compression.
8.4 Application to Other Baleen Whale Species
The uniquely long, loud calls of the blue whale require volume displacements greater than any other whale, limiting model applications primarily
to the blue whale, although similar methods may be applied to other mysticetes. Humpback whale calls, fin whale calls, and the pulsive type "A" and
short duration blue whale calls could all be produced by laryngeal sac contractions alone, the air being recycled between calls or call segments. Table
10.1 lists total volume displacement estimates for a variety of low-frequency
whale calls. If no resonance is present, the minimum flow. There appears to
be insufficient published data to adequately compare laryngeal sac volumes
among species, but Figure 10.22 is a compilation of published data on laryn-
459
the resonance is higher. We also show profile for a flow rate of 251/s corresponding to a Q of 4. The shallower dive profile corresponding to a Q of
4 would indicate the whale called at an intensity less than it is capable
of because it did not use all the air in its lungs, assuming we have the
anatomical volumes correct. The variation in the depth of the blue whale
during calling is the major testable hypothesis of the proposed model.
8.2 A Dive Depth Limit?
A question related more to blue whale anatomy than to sound production
is. Can the blue whale avoid flooding the nasal passages when making deep
dives? If we assume a 2,000-1 lung volume and 200-1 laryngeal sac volume,
both these will be totally collapsed, and all the air will reside in the 100-1
nasal passage volume, at a depth of 220 m (see Eq. 7). Echo-sounder records
show blue whales diving to near 300m depth (Alling et aI.1991), so it seems
the whale must either flood the nasal passage, allow blood or tissue to fill
in the nasal passage, or hold a significant differential pressure. One approach
to estimating the minimum differential pressure a blue whale can hold is to
estimate the pressure associated with a blow. Using the rise time and rise
height to estimate flow velocity and treating the nasal passages as a nozzle
in a fluid dynamics calculation yields differential pressures of 1 to 2 bar, not
enough to allow diving 80m below the lung collapse depth (8 bar).
8.3 Gaps in Call Pattern Should Coincide with Surfacing
The presence of pauses between calls and breathing gaps is consistent with
the physical model presented here in that a type "B" call could not be produced without a depth change to compress or decompress the lung, thus
production of type "B" calls must cease while the whale is at the surface to
breath. The pressure required to compress the lung volume into the volume
on the narial side of the oscillating valve is too great to expect muscle contraction along to provide, thus requiring the depth-related compression.
8.4 Application to Other Baleen Whale Species
The uniquely long, loud calls of the blue whale require volume displacements greater than any other whale, limiting model applications primarily
to the blue whale, although similar methods may be applied to other mysticetes. Humpback whale calls, fin whale calls, and the pulsive type "A" and
short duration blue whale calls could all be produced by laryngeal sac contractions alone, the air being recycled between calls or call segments. Table
10.1 lists total volume displacement estimates for a variety of low-frequency
whale calls. If no resonance is present, the minimum flow. There appears to
be insufficient published data to adequately compare laryngeal sac volumes
among species, but Figure 10.22 is a compilation of published data on laryn-