"My naturesound" - nature observations with sound recordings

Abstract Background Online systems for observation reporting by citizen scientists have been operating for many years. iNaturalist (California Academy of Sciences 2016), eBird (Cornell Lab of Ornithology 2016) and Observado (Observation International 2016) are well-known international systems, Artportalen (Swedish Species Information Centre 2016) and Artsobservasjoner (Norwegian Biodiversity Information Centre 2016) are Scandinavian. In addition, databases and online solutions exist that are more directly research-oriented but still offer participation by citizen scientists, such as the PlutoF (University of Tartu Natural History Museum 2016) platform. The University of Tartu Natural History Museum maintains the PlutoF platform (Abarenkov et al. 2010) for storing and managing biodiversity data, including taxon observations. In 2014, development was started to integrate an observation app "Minu loodusheli"/"My naturesound" (University of Tartu Natural History Museum 2017b) (My naturesound, Fig. 1) within PlutoF system. In 2017, an English language version of the app (University of Tartu Natural History Museum 2017c) was launched that includes nearly all major sound-producing taxon groups in its taxonomy. The application also acts as a practical tool for collecting and publishing occurrence data for the Global Biodiversity Information Facility (Global Biodiversity Information Facility 2017) in standardized Darwin Core format together with download links to the multimedia files. Although the sound recording ability of mobile phones opens new opportunities to validate taxon occurrences, current technological solutions limit the use of recordings in biodiversity research. The "My naturesound" allows the user to record taxon occurrences and to provide audio recordings as evidence. After installing the application, the user is promted to login with PlutoF system credentials or to register with PlutoF. The application is targeted primarely to citizen scientists, but researchers themselves can also use it as a tool for easy annotation of taxon occurrences. New information The dataset consists observation data of birds, amphibians and insects by citizen scientists with on site audio recordings. The dataset gives the possibility to analyze the suitablility of mobile devices for recording animal vocalizations and their use in reporting.

recording ability of mobile phones opens new opportunities to validate taxon occurrences, current technological solutions limit the use of recordings in biodiversity research.
The "My naturesound" allows the user to record taxon occurrences and to provide audio recordings as evidence. After installing the application, the user is promted to login with PlutoF system credentials or to register with PlutoF. The application is targeted primarely to citizen scientists, but researchers themselves can also use it as a tool for easy annotation of taxon occurrences.

Introduction
The availability and affordability of smartphones have encouraged the use of mobile applications for nature observations. There are many well-known mobile applications that allow observers to annotate taxon occurrences and to add important data, such as date, The application interface on the Android patform. time and coordinates, automatically from the mobile device itself, e.g. iNaturalist, eBird and Anymals+Plants (SiSol Systems 2015). As all modern smartphones are equipped with an easy to operate camera, adding a photo to a taxon observation is easy with plants, some mammals or less mobile insects. Photos can be used to aid identification, although the observer may not be aware of which aspect of the taxon is most important and needs to be clearly in focus or properly displayed. Taking mobile photos of distant animals provides much poorer resolution, thereby hindering indentification. While photography is widely used for observation applications (iNaturalist, eBird), audio recordings of nature observations are far less common. Although applications for mobile phones exist for use as the voice recorder (Samsung Voice Recorder, TapeMachine, Field Recorder etc on Android devices), few apps are used to provide an audio recording to a taxon observation. The benefits of this feature are obvious -even a mediocre sound recording of a bird hidden in the bushes can aid identification more than relying solely on a mobile photo at distance.
Although audio recording by mobile phones opens new opportunities for validation of biodiversity observations, there remain important limitations. Mobile phone sound processing is usually designed for human speech, thereby filtering certain frequencies.
Also, recording capability is limited by the frequency response of the microphone unit and the sampling rate of the smartphone software (Brown and Evans 2011). We did not address these issues specifically in our project, but those using audio files recorded with mobile phones for research should be aware of these limitations. "Minu loodusheli"/"My naturesound" is a mobile app developed by University of Tartu Natural History Museum in cooperation with the Estonian Natural History Museum. This app helps to annotate observations of a specific taxon and add a audio recording from the location of the observed specimen. The app is backed by the cloud database and workbench PlutoF, specifically designed for working with taxon occurrences and related biodiversity data. Both the mobile app and PlutoF workbench are also considered optimal for the European Biodiversity Observation Network (EU BON 2016) project. Collected data are published on the GBIF portal for download as Darwin Core Archive package, EML package or annotated GBIF data package.
The app is currently available for both Android and iOS platforms, but as the iOS version will not be updated for financial reasons, newer phones and operation system versions may not be compatible with the app.

Project description
Title: "My naturesound" -nature observations with sound recordings.

Study area description:
Observation area is not restricted, but as most users live in Estonia, the observations are mostly from Estonia.

Design description:
The mobile application enables the user to store observation data: date (aquired automatically), location (aquired automatically if GPS is switched on, otherwise manually using map application) and taxon (species-level identification or higher taxon level identification). As the application is intended mostly for citizen scientists, there are no obligatory data fields for environmental parameters, although the user can add additional information as remarks. Moreover, the PlutoF workbench allows later addition of data fields when working with uploaded observation data. Recording and adding an audio file to the observation is a prerequisite for app data flow; adding an image is optional. All observation data are linked to the user's profile and are transmitted via data upload to the cloud database. The app can be used offline for recording therefore the availability of mobile networks will not limit the use of the app in the field. The app uses PlutoF customized API protocol to upload data (University of Tartu Natural History Museum 2016).
Once the data have been stored in PlutoF cloud database and made publicly available, all registered database users can access the observation data and audio files for research purposes. For example, if a user executes a search for observations of Great Tit (Parus major L.) with audio files attached, all such observations obtained via "My naturesound" app will be also retrieved and displayed (Fig. 2). If a single observation record is opened, the audio file can be downloaded (Fig. 3) and analyzed in the user's computer with appropriate software. The audio file properties -type, format, original name, size etc -can also be viewed on the PlutoF workbench when the file properties menu is open (Fig. 4). As retrieval of audio file metadata from mobile phones is less straightforward than image files, the metadata of audio file is limited. In addition, privacy issues concerning citizen science projects must be adhered to when retrieving information from users' phones. As PlutoF biodiversity data are regularily published on GBIF, all aforementioned information can be also retrieved from the GBIF data portal (Fig. 5). Occurrence record view also includes multimedia file information with a link to the actual audio file, which can be listened to and downloaded (Fig. 6).    The details of an occurrence record viewed on GBIF platform.

Study extent: World
Sampling description: Mostly observations by citizen scientists using mobile application to record coordinates and time of observation and adding audio recordings to the observation. Adding an audio file is obligatory when using the application, otherwise observations cannot be sent to database.
Quality control: All observations include a audio recording used for species identification. Recordings are reviewed on the PlutoF workbench. Incorrect identifications are corrected; the observation with inappropriate recordings are rejected.
Step description: Observations are recorded with the mobile app "Minu loodusheli" (My naturesound), observation records with audio files are transferred to the PlutoF cloud database. Observations are reviewed within PlutoF system by appointed persons.

Geographic coverage
Description: App users can make observations throughout the world; there are no geographical limitations. As the promotion of the application is mostly in Estonian, majority of observations are also from Estonia (Fig. 7). Description: Sound-based taxon occurrences provided by citizen scientists through the PlutoF workbench and connected mobile application "Minu loodusheli" (My naturesound). Every occurrence can be validated via accompanying audio recording. The dataset consists of two tables which for practical reasons are considered as individual datasets -one for occurrences (59 data columns) and the other for audio files linked to each occurrence (12 data columns). Multimedia files are referred in the data table by url and can be downloaded individually through the PlutoF workbench if the file owner has granted access to the files. All information is in English, except the "occurrenceRemarks" and "identificationRemarks" columns, which can be in set to the application user's choice.

Column label Column description
id Record ID type The nature or genre of the resource. For Darwin Core, recommended best practice is to use the name of the class that defines the root of the record. locationID An identifier for the set of location information (data associated with dcterms:Location). country The name of the country or major administrative unit in which the Location occurs.
countryCode The standard code for the country in which the Location occurs. Recommended best practice is to use ISO 3166-1-alpha-2 country codes. stateProvince The name of the next smaller administrative region than country (state, province, canton, department, region, etc.) in which the Location occurs.
county The full, unabbreviated name of the next smaller administrative region than stateProvince (county, shire, department, etc.) in which the Location occurs.

municipality
The full, unabbreviated name of the next smaller administrative region than county (city, municipality, etc.) in which the Location occurs. Do not use this term for a nearby named place that does not contain the actual location. locality The specific description of the place. Less specific geographic information can be provided in other geographic terms (higherGeography, continent, country, stateProvince, county, municipality, waterBody, island, islandGroup). This term may contain information modified from the original to correct perceived errors or standardize the description.

minimumElevationInMeters
The lower limit of the range of elevation (altitude, usually above sea level), in meters.

maximumElevationInMeters
The upper limit of the range of elevation (altitude, usually above sea level), in meters.

minimumDepthInMeters
The lesser depth of a range of depth below the local surface, in meters.

maximumDepthInMeters
The greater depth of a range of depth below the local surface, in meters.  kingdom The full scientific name of the kingdom in which the taxon is classified. phylum The full scientific name of the phylum or division in which the taxon is classified. class The full scientific name of the class in which the taxon is classified. order The full scientific name of the order in which the taxon is classified. family The full scientific name of the family in which the taxon is classified. genus The full scientific name of the genus in which the taxon is classified. subgenus The full scientific name of the subgenus in which the taxon is classified. Values should include the genus to avoid homonym confusion. specificEpithet The name of the first or species epithet of the scientificName. infraspecificEpithet The name of the lowest or terminal infraspecific epithet of the scientificName, excluding any rank designation. taxonRank The taxonomic rank of the most specific name in the scientificName.
Recommended best practice is to use a controlled vocabulary. verbatimTaxonRank The taxonomic rank of the most specific name in the scientificName as it appears in the original record.