Acoustic recordings of underwater vocalizations of Indo-Pacific humpback dolphins in Xiamen Bay, China

To adapt to the complex and dark underwater environment, dolphins have evolved the ability to use sound for sensing their surroundings, navigation, foraging, and communication. Dolphin vocalizations primarily consist of two main types: pulsed signals and frequency-modulated communication whistles. Pulsed signals, including echolocation clicks, burst pulses, and buzzes, are characterized by high-frequency, broadband properties and are typically produced in trains. Whistles are narrow-band signals with modulated frequencies and are predominantly used for communication. Dolphin vocalizations are complex and dynamic yet critical for their survival. Analysis of dolphin vocalizations provides valuable insights into their behaviors and population status.

Acoustic data in this dataset were collected using an autonomous underwater recorder in Xiamen Bay, China, which is inhabited by a small population of Indo-Pacific humpback dolphins.

Original Audio File.zip is a compressed file containing the original recordings, including 35 WAV audio files sequentially named according to the recording time (e.g., Ori_Recording_01.wav, Ori_Recording_02.wav, Ori_Recording_03.wav).

Whistles.zip comprises 143 identified whistle signals saved as individual sequentially-named WAV files (Whistle_001, Whistle_002, Whistle_003, etc), accompanied by PNG image files illustrating their respective spectrograms. Whistle signals were mannually extracted from the original recordings, of which 100 were identified as high-quality based on visual inspection. Each whistle signal was visually categorized into one of six tonal types. Subsequently, 13 key acoustic parameters were manually measured from the spectrograms of the high-quality whistles. These 13 parameters were: duration, start frequency, end frequency, frequency change, absolute frequency gradient, minimum frequency, maximum frequency, delta frequency, number of extrema, number of inflection points, number of saddle points, number of breaks, and presence/absence of harmonics. Detailed information was presented in the Excel spreadsheet named "Whistles.xlsx".

Click Trains.zip, Burst Pulse Trains.zip, and Buzz Trains.zip contain WAV audio files corresponding to the detected click trains, burst pulse trains, and buzz trains, respectively. Pulse signals were detected and classified following the published methodologies and procedures. After manual verification, a total of 897 pulse trains were included in the dataset, comprising 832 echolocation click trains, 15 burst pulse trains, and 50 buzz trains. Each pulse train, along with its constituent individual pulses, were saved as separate WAV files in a separate subfolder. These subfolders were sequentially named according to the chronological order of the pulse train (e.g., PulseTrain_001, PulseTrain_002, PulseTrain_003). For each pulse train, six acoustic parameters were measured for the pulsed signals: (a) inter-pulse-interval (IPI), (b) sound pressure level (SPLpp), (c) duration, (d) peak frequency (Fpeak), (e) -3dB bandwidth (-3dBBW), and (f) -10dB bandwidth (-10dBBW). Values of these parameters were presented in a tab-separated TXT file named “PulseParameters.txt”, which was included in the subfolder.

Results.xlsx is an Excel file containing detailed information on the original acoustic recordings and quantitative data on whistles and pulsed signals detected within each original acoustic file:
1. recording dates when the original acoustic data were collected;
2. Geographic coordinates (latitude and longitude) of the recording locations;
3. start and end times of each original acoustic file;
4. number of pulse trains detected within each original acoustic file;
5. number of identified whistles, including counts of high-quality whistles (Grade 2 and 3) for each original acoustic file;
6. additional information about the recordings, including seasons, tides, water depth, dolphin group size, and behavioral state of dolphins.

Whistles.xlsx is an Excel file that provides detailed descriptions of each whistle signal:
1. the original acoustic file from which the whistle signal was extracted;
2. start and end times of each whistle signal within the original acoustic file, relative to the file’s start, expressed in seconds;
3. contour type classification for each whistle signal (constant, upsweep, downsweep, concave, convex, and sinusoidal);
4. quality grading for each whistle (Grade 1, Grade 2, and Grade 3);
5. acoustic parameters of each whistle signal: Duration, Start Frequency, End Frequency, Frequency Change, Absolute Frequency Gradient, Minimum Frequency, Maximum Frequency, Delta Frequency, Number of Extrema, Number of Inflection Points, Number of Saddle Points, Number of Breaks, and Presence/Absence of Harmonics.

ClickTrains.xlsx, BurstPulseTrains.xlsx, and BuzzTrains.xlsx are Excel files containing detailed information on each identified pulse train type:
1. serial number of pulse trains denoting their order of appearance within original recordings;
2. original acoustic file from which each pulse train was extracted;
3. start and end times of each pulse train within the original acoustic file, relative to the file’s start, expressed in seconds;
4. lengths of each pulse train (Length);
5. number of pulsed signals within each pulse train (NumP);
6. mean values of acoustic parameters of the pulsed signals within each pulse train: mean SNR (Mean_SNR), mean IPI (Mean_IPI), mean sound pressure level (Mean_SPLpp), mean duration (Mean_Duration), mean peak frequency (Mean_Fpeak), mean -3dB bandwidth (Mean_-3dBBW), and mean -10dB bandwidth (Mean_-10dB BW).

Further information is provided in the accompanying Data Descriptor published in Scientific Data.