Speech intelligibility in a stationary multipath channel.

Sachs, Murray B.; O'Brien, G.J.; Sergeant, Russell L.; Russotti, Joseph S.

doi:10.1037/e443752004-001

Cited by 4 publications

(3 citation statements)

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“…The broadening of pulse transmission is therefore a nuisance to sonar detection and underwater communications ͑Urick, 1967; Atkinson, 1974;Sachs et al, 1968͒. On the other hand it has been shown ͑Smith, 1971; Harrison, 2003a͒ that the pulse shape contains easily extractable environmental information. So for both reasons the shape of the pulse and its dependence on environmental properties are of interest.…”

Section: Introductionmentioning

confidence: 99%

Multipath pulse shapes in shallow water: Theory and simulation

Harrison

Nielsen

2007

The Journal of the Acoustical Society of America

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In shallow water propagation the steeper ray angles are weakened most by boundary losses. Regarding the sound intensity as a continuous function of angle it can be converted into a function of travel time to reveal the multipath pulse shape received from a remote source (one-way path) or a target (two-way path). The closed-form isovelocity pulse shape is extended here to the case of upward or downward refraction. The envelope of the earliest arrivals is roughly trapezoidal with a delayed peak corresponding to the slowest, near horizontal refracted paths. The tail of the pulse falls off exponentially (linearly in decibels) with a decay constant that depends only on the bottom reflection properties and water depth, irrespective of travel time, a useful property for geoacoustic inversion and for sonar design. The nontrivial analytical problem of inverting explicit functions of angle into explicit functions of time is solved by numerical interpolation. Thus exact solutions can be calculated numerically. Explicit closed-form approximations are given for one-way paths. Two-way paths are calculated by numerical convolution. Using the wave model C-SNAP in several broadband cases of interest it is demonstrated that these solutions correspond roughly to a depth average of multipath arrivals.

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Section: Introductionmentioning

confidence: 99%

Multipath pulse shapes in shallow water: Theory and simulation

Harrison

Nielsen

2007

The Journal of the Acoustical Society of America

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“…Based on the data at hand, the nature of the speech signal passing through water would tend to favor a directional receiving apparatus. Sachs et. al.…”

Section: Discussionmentioning

confidence: 99%

Intersubmarine Speech Intelligibility Levels

Murry¹,

Strand²

1971

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To determine speech intelligibility levels between submarines using standard submarine communication units. FINDINGS Speech intelligibility scores ranged from 31.0 to 79.4 percent. The intelligibility scores appeared to vary as a result of the mode of transmission and reception and as the result of depth of the transmitter and receiver units. APPLICATION The results of this study deal directly with the problem of communication between two submarines. The results suggest that directional transmission is superior and should be implemented when the two submarines are operating at the same depth. Conversely when operation is at two different depths an omnidirectional transmission mode is suggested.

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“…Speech that has been passed through an acoustic channel such as the ocean is distorted by the phenomenon known as "time-smearing" (See Sachs, et al, 1969) 3 . If an underwater source and a somewhat distant receiver are both situated relatively close to the surface of the ocean, the sound radiated from the source may travel toward the receiver over several different pathways.…”

Section: Introductionmentioning

confidence: 99%