NT-21-X14:Low Frequency Hearing In Pinnipeds | M22AS00135

Opportunity Information: Apply for M22AS00135

NT-21-X14: Low Frequency Hearing in Pinnipeds is a Bureau of Ocean Energy Management (BOEM) research award focused on filling a major data gap in what is known about how seals and sea lions hear very low-frequency underwater sounds. The core idea is straightforward but technically challenging: scientists build an audiogram (a hearing curve) by repeatedly presenting an animal with pure tones at specific frequencies and sound levels to find the quietest level the animal can detect at each frequency (the auditory threshold). After establishing those baseline thresholds, the researchers add noise in controlled frequency bands to see how much the noise raises the detection threshold (a "masked threshold"). By widening the noise band step by step, they identify the point at which adding even more bandwidth no longer makes the tone harder to detect; that point is the "critical bandwidth." From that, they can derive the animal's auditory filter properties and estimate the "critical ratio," a psychoacoustic measure that describes how detectable a tone is when embedded in noise (essentially the tone-to-noise power relationship required for detection under these test conditions). Together, these measures provide clues about cochlear function and frequency selectivity, not just raw sensitivity.

The opportunity exists because, despite decades of marine mammal hearing research and major synthesis work such as Southall et al. (2007), pinniped hearing has rarely been measured below 100 Hz. Several species now have published audiograms (including harbor seals, spotted seals, ringed seals, and California sea lions), but those datasets largely stop at or above 100 Hz. The reason is not a lack of interest so much as practical physics and engineering constraints: in tank settings, very low-frequency sound has long wavelengths that can create strong standing waves and uneven sound fields, which complicates calibration and makes it difficult to know what sound exposure the animal is truly receiving. On top of that, many underwater transducers are not designed to generate clean, powerful tones at these very low frequencies. As a result, there is limited empirical information about auditory filters and critical bandwidths in pinnipeds at the lowest frequencies, even though work across mammals has often suggested critical bandwidths on the order of about one-third of an octave in many contexts. Without direct measurements below 100 Hz, it is uncertain whether that general pattern holds for pinnipeds in the infrasonic-to-low-audible underwater range.

This project is designed to provide the first measurements of hearing sensitivity and frequency selectivity below 100 Hz in two key pinniped species: the California sea lion and the bearded seal. Ongoing related work funded through the Sound and Marine Life Joint Industry Program has already been testing bearded seals at 63 Hz and 100 Hz, but it has not extended to frequencies below 63 Hz, and previous California sea lion studies have not gone lower than 100 Hz. BOEM highlights the importance of pushing into these lower frequencies because many human-made offshore and coastal sound sources have substantial energy in exactly this range. Examples called out in the description include seismic airguns, marine vibroseis systems, and pile-driving, all of which can produce prominent low-frequency components that propagate efficiently underwater and may overlap with pinniped hearing capabilities. By clarifying where thresholds lie and how masking behaves at low frequencies, the study aims to improve the scientific basis for evaluating potential impacts of industrial and construction noise on these animals and, by extension, to inform management decisions tied to BOEM's offshore energy and environmental responsibilities.

Administratively, the opportunity is issued as a discretionary cooperative agreement under an environmental funding activity category (CFDA 15.423). It is described as a single-source cooperative agreement with the University of California, Santa Cruz, meaning it is intended for a specific recipient rather than a broad open competition. The funding opportunity number is M22AS00135, the original closing date listed is 2022-04-28, the expected number of awards is one, and the award ceiling is $200,000. In practical terms, the grant supports a targeted research effort to generate foundational low-frequency hearing and masking data that are currently missing from pinniped audiology, with direct relevance to assessing and managing low-frequency noise introduced by offshore activities.

• The Bureau of Ocean Energy Management in the environment sector is offering a public funding opportunity titled "NT-21-X14:Low Frequency Hearing In Pinnipeds" and is now available to receive applicants.
• Interested and eligible applicants and submit their applications by referencing the CFDA number(s): 15.423.
• This funding opportunity was created on 2022-03-29.
• Applicants must submit their applications by 2022-04-28. (Agency may still review applications by suitable applicants for the remaining/unused allocated funding in 2026.)
• Each selected applicant is eligible to receive up to $200,000.00 in funding.
• Eligible applicants include: Others.

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