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FAQs:Optional User Spreadsheet

What is the purpose of the Optional User Spreadsheet?

The Optional User Spreadsheet  is a companion spreadsheet associated with the alternative methodology provided in Appendix D of the Technical Guidance. NMFS recognizes in updating our acoustic thresholds to reflect the scientific literature, they have become more complex. The User Spreadsheet provides a set of alternative tools and weighting factor adjustments (WFAs) to allow action proponents with different levels of exposure modeling capabilities to be able to accurately apply NMFS’ updated acoustic thresholds for the onset of PTS for all sound sources.

The User Spreadsheet includes multiple conservative assumptions and therefore would be expected to typically result in higher estimates of instances of hearing impairment than more sophisticated methodology. The larger the scale of the activity, the more these conservative overestimates would be compounded if the alternative methodologies were used.

Are action proponents required to rely upon the User Spreadsheet?

No, there are no requirements to use the User Spreadsheet. The User Spreadsheet is provided as an optional tool for those action proponents who wish to use it.

How does one use the User Spreadsheet?

It is advised that one starts with the User Spreadsheet’s white “Introduction” tab that provides general guidance on how to use the User Spreadsheet. This “Introduction” tab will help a user decide which tab (spreadsheet) is most appropriate for their particular sound source (i.e., tabs A through F). Once the appropriate tab is determined, a user must fill out the appropriate sage (action proponent provided information) cells associated with Steps 1 through 3. Once this is completed, the resultant PTS isopleths to thresholds (sky blue cells) are provided. When relying upon this User Spreadsheet to estimate isopleths, please provide a copy of the completed spreadsheet. Note: For impulsive sounds, action proponent must also consider isopleths peak sound pressure level (PK) thresholds (dual thresholds), which are not provided via the User Spreadsheet.

I am interested in using the optional User Spreadsheet to determine PTS onset isopleths associated with vibratory pile driving activities. Do I use the yellow B) “Non-impulsive-Stationary-Intermittent” tab?

No. The recommended tab for vibratory pile driving activities is the red A) “Non-impulsive-Stationary-Continuous” tab. While it is recognized that vibratory pile driving is rarely 100% continuous, the intent of the “intermittent” tabs are for those sound sources that have a more regularly defined pulse duration and repetition rate, unlike vibratory pile driving.

It is recommended that the following tabs be used for these common sources:

What is the difference between the green E) “Impulsive-Stationary” and the evergreen E.1) “Impact Pile Driving” tabs?

The only difference between the green E) and evergreen E.1) tabs is that tab E.1 “Impact Pile driving” asks for source characteristics (sage action proponent provided information) that are more reflective (user-friendly) of activity-specific characteristics/descriptions associated with impact pile driving (i.e., strikes per pile; piles per day). As an example, the more generic green E) “Impulsive-Stationary” tab could be used for sound sources such as stationary vertical seismic profiles (VSP).

What is being asked for in the sage (action proponent provided information) cell labeled “1/repetition rate”?

The sage (action proponent provided information) cell labeled “1/repetition rate” refers to the time between the onset of successive pulses. For example, if a sound source produced a 9-second pulse, there is a silent period of 4 seconds, and then another 9-second pulse is produced, the repetition rate for this sound source would be 1/13 seconds (i.e., 9-second pulse plus 4-second silent period before the start of another 9-second pulse). Thus, 1/repetition rate would be 13 s, which is the value that would be entered in the sage (action proponent provided information) cell.

What if there are two methods for providing source-specific information (Step 3)? Which method should be used?

The User Spreadsheet’s intent in providing multiple methods for determining PTS isopleth to thresholds is to allow the user flexibility in the type of information (source characteristics) provided. Action proponents are advised to use the method which provides the most accurate representation of their activity. Action proponents may decide which method to use and are not required to fill out the sage (action proponent provided information) associated with both methods (i.e., action proponents use one method OR the other, not both).

What are the biggest changes/considerations associated with the Technical Guidance and User Spreadsheet in terms of information needed from action proponents?

The two biggest changes associated with the Technical Guidance/User Spreadsheet is the consideration of 1) Duration of exposure (e.g., activity duration within a 24-h period) associated with the Technical Guidance’s cumulative sound exposure level (SELcum) thresholds and 2) marine mammal weighting functions, which take into account what is known about marine mammal hearing sensitivity and susceptibility to noise-induced hearing loss. The User Spreadsheet incorporates optional methodology for accounting for both these factors.

Are there standard pieces of information that can be used to help fill-in sage cells (action proponent provided information)?

Sage (action proponent provided information) cells should be filled-out based on activity-specific information. There are some default values available, if activity-specific information is unavailable (i.e., weighting factor adjustments). Action proponents will need to provide basic information about their activity (e.g., source level, source velocity (if mobile), factors associated with activity duration) or find suitable surrogates to supply this information.

What is the Weighting Factor Adjustment (WFA)?

Numerical criteria presented in the Technical Guidance consist of both an acoustic threshold and auditory weighting function associated with the SELcum metric. NMFS recognizes that the implementation of marine mammal weighting functions represents a new factor for consideration, which may extend beyond the capabilities of some action proponents. Thus, NMFS has developed simple weighting factor adjustments (WFA) for those who cannot fully apply auditory weighting functions associated with the SELcum metric.

WFAs consider marine mammal auditory weighting functions by focusing on a single frequency. This will typically result in similar, if not identical, predicted exposures for narrowband sounds or higher predicted exposures for broadband sounds, since only one frequency is being considered, compared to exposures associated with the ability to fully incorporate the Technical Guidance’s weighting functions. WFAs have the advantage of allowing everyone to use the same acoustic thresholds and allows for adjustments to be made for each hearing group based on source-specific information. Note: For broadband sources, there are specific considerations associated with the WFA chosen. Please see the gray “Weighting Factor Adjustment” tab in the User Spreadsheet (last tab) for more information.

I keep getting an error when trying to use the User Spreadsheet. Why is this happening?

To have the User Spreadsheet successfully provide PTS isopleths to threshold, it is necessary that the user fill in all appropriate sage (action proponent provided information) cells, including Step 2: Weighting Factor Adjustment (WFA). If an input is not provided for Step 2, then isopleths cannot be calculated.

NMFS realizes accounting for marine mammal weighting functions, which is the purpose of Step 2, is a new consideration for most action proponents. Thus, if action proponents are unable to provide a project-specific WFA, a default (found on white “Introduction” tab of User Spreadsheet, Rows 60-65) may be used. It is critical that the action proponent indicate whether a default value or project-specific information is used to support the WFA chosen. Note: For broadband sources, there are specific considerations associated with the WFA chosen. Please see gray “Weighting Factor Adjustment” tab in the User Spreadsheet (last tab) for more information.

How/when will the User Spreadsheet be updated?

The white “Introduction” tab (starting on Row 95) includes information on updates associated with the User Spreadsheet. Additionally, Row 2 of the “Introduction” tab provides information on the current version number and date of last update.

Who do we contact if we have questions about the User Spreadsheet?

If you have questions about the User Spreadsheet, please contact: Amy Scholik-Schlomer (; 301 427-8449).

Updated: August 30, 2016