5. Acoustics and Social Behavior
255
measurable structural features as duration of a signal, amplitude, changes
in rate of delivery, shifts in frequency, or relational features of signals (a
signal may be merely louder or longer than the previous one). Prosodic or
rhythmic features of communication are critical for broad activity, but can
also contain subtle identity information of the escalation of impending
behavioral changes. A human observer in the water may, at a distance, hear
a combination of types of signals that may indicate the general state of
activity (e.g., fighting, foraging). If the level of general activity (Herzing,
unpublished data), and the diversity of sounds present and audible distances of up to 2km (dos Santos et al. 1995) can be obtained by a listening
human, then dolphin decoding must contain much more complicated levels
of analyses. Potentially contained within conspecific signals are individual
identifiers, emotive information, and other changes in behavioral states, possibly discernible to the experienced dolphin who has previously observed,
interacted, and participated in conflict resolution.
6. Special Cases of Communication
A review of the sensory and cognitive literature of dolphins reveals that
their capabilities may include the following:
1. Cross-modal perception: intermodal transfer of information is relevant when dolphins synchronously generate visual images from audition
signals and the reverse. Pack and Herman (1995) report that dolphins
recognized complex shapes across the visual and acoustic sense. Similar
cross-modal results have been obtained by Azzali et al. (1995). However,
an alternative interpretation to cross-modal representation has been
discussed (Popper et al. 1997).
2. Feature detection and filtering to provide minimal information
(Herman et al. 1990).
3. The presence and absence of objects, comprehension of syntactical
rules, and two-dimensional representations in space of abstract television
images and time displacement (Herman et al. 1990).
4. Shared listening and eavesdropping: the ability to eavesdrop and glean
information through the return echoes of conspecifics (Xitco and Roitblat
1996), also termed "interception" in fish communication (Myrberg 1981).
Although the distance and position to the source of the active echolocation
clicks is critical, this provides some suggestion that dolphins may have the
ability to share information as a group.
5. Signature decoding may be unique enough to extract pertinent
features (Au and Moore 1988).
6. Synchrony, imitation, and mimicry (Xitco 1988).
Support for the application of these capabilities of dolphins in the wild
include: the ability to encode, store, and retrieve information including indi-
255
measurable structural features as duration of a signal, amplitude, changes
in rate of delivery, shifts in frequency, or relational features of signals (a
signal may be merely louder or longer than the previous one). Prosodic or
rhythmic features of communication are critical for broad activity, but can
also contain subtle identity information of the escalation of impending
behavioral changes. A human observer in the water may, at a distance, hear
a combination of types of signals that may indicate the general state of
activity (e.g., fighting, foraging). If the level of general activity (Herzing,
unpublished data), and the diversity of sounds present and audible distances of up to 2km (dos Santos et al. 1995) can be obtained by a listening
human, then dolphin decoding must contain much more complicated levels
of analyses. Potentially contained within conspecific signals are individual
identifiers, emotive information, and other changes in behavioral states, possibly discernible to the experienced dolphin who has previously observed,
interacted, and participated in conflict resolution.
6. Special Cases of Communication
A review of the sensory and cognitive literature of dolphins reveals that
their capabilities may include the following:
1. Cross-modal perception: intermodal transfer of information is relevant when dolphins synchronously generate visual images from audition
signals and the reverse. Pack and Herman (1995) report that dolphins
recognized complex shapes across the visual and acoustic sense. Similar
cross-modal results have been obtained by Azzali et al. (1995). However,
an alternative interpretation to cross-modal representation has been
discussed (Popper et al. 1997).
2. Feature detection and filtering to provide minimal information
(Herman et al. 1990).
3. The presence and absence of objects, comprehension of syntactical
rules, and two-dimensional representations in space of abstract television
images and time displacement (Herman et al. 1990).
4. Shared listening and eavesdropping: the ability to eavesdrop and glean
information through the return echoes of conspecifics (Xitco and Roitblat
1996), also termed "interception" in fish communication (Myrberg 1981).
Although the distance and position to the source of the active echolocation
clicks is critical, this provides some suggestion that dolphins may have the
ability to share information as a group.
5. Signature decoding may be unique enough to extract pertinent
features (Au and Moore 1988).
6. Synchrony, imitation, and mimicry (Xitco 1988).
Support for the application of these capabilities of dolphins in the wild
include: the ability to encode, store, and retrieve information including indi-