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Background

The overall goal of Phase 1 is to create and describe a large-scale, multi-talker database of speech stimuli to be used in future high-variability training studies (e.g., in Phase 2). The database will include speech stimuli recorded and analyzed acoustically by each of the participating project teams. The database is envisaged as an open-source repository of various sets of training materials (e.g., targeting the voiced vs. voiceless contrast in Spanish stops, oral vs. nasal contrast in Brazilian Portuguese vowels, long vs. short opposition in Finnish consonants) accompanied by detailed specifications of the variability within each set along relevant acoustic/phonetic dimensions. The database will also include comparable demographic data for all talkers.


An anticipated outcome of Phase 1 is a joint multi-authored manuscript to be submitted for review and potential publication under the Data Report category in Studies in Second Language Acquisition. All participating team members will be invited to review and sign a collaborator agreement and to co-author this manuscript (see the timeline below to review and upload your collaborator agreement).

How much intra- and inter-individual variation in the target acoustic dimension(s) is available in each training set?

This question targets one fundamental yet underexplored issue underlying potential benefits of high-variability training: the extent to which the training materials are variable along relevant acoustic/phonetic dimensions. Each team’s goal in Phase 1 is to create and describe their recorded stimulus set in terms of the variability within it.

There are several elements of Phase 1 study design that are fixed for all participating research teams. Each team will commit to record and analyze:

    • exactly 8 talkers total (4 men, 4 women) per selected target category
    • with a minimum of 10 items (e.g., words, phrases, sentences – as relevant) per target category


Each team will also be provided with:

    • a background questionnaire
    • templates of IRB/ethics applications to be customized for site-specific requirements


The remaining methodological decisions for recording and analysis will be made by each participating team with reference to the specific research target and context (see the timeline below to complete and upload a detailed description of Phase 1 initial study plan).

The acoustic analysis of each team’s recorded stimulus set will depend on the selected target and the expertise within each participating team. The goal of acoustic analysis, in each case, is to establish descriptively how much intra- and inter-individual variation in the target acoustic dimension(s) is present in the recorded stimulus set. Descriptive approaches might include, but are not limited to, the use of variability metrics (e.g., standard deviation, dispersion) and perceptual/acoustic metrics (e.g., Mel, Bark, Euclidean distances). Once we receive input from all teams, we will connect teams working on the same or similar targets so that they can align their analytical approach and, where possible, adopt shared analytical procedures.

To write up their findings for eventual inclusion in a joint manuscript, each participating team will receive a reporting template with instructions to fill in brief sections about the recorded stimulus set, recording procedures, carried out analyses, and findings. To the extent possible, the template will be brief and simple, with fillable spaces, tables, or instructions for creating R-based graphics.

Timeline

December 2025

Task 0

Complete a brief expression of interest survey (Qualtrics)

16 February 2026

Task 1

Submit Phase 1 Initial Study Plan (.docx format preferred)

 
Documents you need

OPL Phase 1 Initial Study Plan (template)

OPL Phase 1 Initial Study Plan (sample entry - use as an example)

Outcome

Receive feedback from PRA team

February 2026

Task 2

Review collaborator agreement

Documents you need

Collaborator agreement (draft)

February–March 2026

Task 3

Complete site-specific ethics/IRB application using templates of ethics/IRB applications

29 April 2026

Task 4

Sign and upload collaborator agreement (.pdf format preferred)

 
Documents you need

Collaborator agreement (final version)

Each individual research team member should sign, date, and upload a copy of this agreement

29 April 2026

Task 5

Submit Phase 1 Version of Record Study Plan (.docx format preferred)

 
Documents you need

OPL Phase 1 Version of Record Study Plan (template)

Outcome

Version of record stored on project's OSF profile

31 May 2026

Task 6

Submit approved IRB/ethics documents (.pdf format preferred)

 
Documents you need

Your completed and approved IRB/ethics application

Outcome

Approvals stored on project's OSF profile

March–May 2026

Task 7

Recruit and record talkers at each research site

June–August 2026

Task 8

Prepare and acoustically analyze stimuli

Fall 2026

Task 9

Finalize stimuli, finish acoustic analysis, write and submit Phase 1 results (.docx format preferred)

 
Documents you need

Writing up results of Phase 1 (template)

Frequently asked questions

We would initially like to hear from you about how you propose to carry out the acoustic analysis for your selected target. Once we receive input from all local teams, we will connect teams working on the same or similar targets so that they can align their analytical approach and, where possible, adopt a shared analysis plan. Share your ideas about your preferred acoustic analyses under Phase 1 Initial Study Plan (see Timeline under February 2026).

We expect that individual researchers and research teams already have basic research skills required for participant recruitment, audio recording, and audio file manipulation. We will provide instructions on specific data analysis procedures or skills needed for Phase 1 (e.g., audio file normalization procedures) and Phase 2 (using Gorilla to deliver and evaluate high-variability training). We will also offer suggestions about acoustic analyses in Phase 1 but the final decisions about how to best analyze variability in the selected target category will be made by individual researchers and research teams.

Individual researchers and research teams are welcome to participate in Phase 1 without committing to Phase 2. More detailed information about Phase 2 will be shared later in the year, at which point teams can decide whether participation is feasible for them.

One anticipated outcome of Phase 1 is a joint multi-authored manuscript to be submitted for review and potential publication under the Data Report category in Studies in Second Language Acquisition. All participating team members will be invited to review and sign a collaborator agreement and to co-author this manuscript. This does not prevent individual researchers or research teams from using the stimuli recorded and analyzed in Phase 1 for other individual projects.