Ninja Listening Trainer Firefox

Ninja Listening Trainer

Mark a YouTube fragment and replay it through a customizable speed/subtitle sequence for listening and pronunciation practice.

Features & Capabilities

Ninja Listening Trainer is a specialized browser extension designed to bridge the gap between textbook pronunciation and natural, real-world spoken language. Whether you are practicing shadowing, analyzing fast native speech, or conducting acoustic perception research, this tool gives you precise control over media playback and step-by-step training sequences.

  • Instant Marking: Set precise Start and End points on any YouTube video or direct local audio file with millisecond accuracy.
  • Custom Step Sequences: Seamlessly iterate through dynamic playback speed programs—from slow anchor speeds ($0.6\times$) up to time-compressed challenge speeds ($2.0\times$).
  • Automatic Subtitle Sync: Toggle captions on or off automatically per step to force acoustic listening before relying on textual support.
  • Optional VAS (Visual Analogue Scale) Ratings: Turn on Research Mode to assess your acoustic and phonological perception clarity at each step.
  • Phonetic-Level Feedback: Measure how clearly you perceive individual sounds, phonemes, and syllables—not just general word boundaries.
  • One-Click Data Export: Save your session ratings, timestamps, and playback configs into clean CSV or JSON files for statistical analysis (ANOVA, Pandas, R) or study logging.
  • Built-in Experimental Protocols: Instant 1-click access to the Ninja Protocol ($0.6\times$ Anchor $\rightarrow 2.0\times$), Pure Compression, and Static Control modes.
  • Load Custom Configs: Import/export standardized lesson files (.json) to share study protocols with students, study groups, or experiment participants.
  • Local Media Support: Works natively on YouTube (youtube.com/watch) as well as local audio and video files opened directly in Firefox.
  1. Mark Your Target: Navigate to a video/audio segment and click Mark start and Mark end.
  2. Choose Your Preset: Select the Ninja Protocol or load a custom step configuration.
  3. Run Sequence: Click ▶ Run sequence to begin your step-by-step listening practice.
  4. (Optional) Check Collect VAS Ratings in the controls panel if you want to record perceptual clarity scores after each iteration and export your dataset.
Designed for language learners, English Speaking Society (ESS) practice, shadowing enthusiasts, and speech perception research.

User Growth & Download Statistics

Manifest V3 Add-on
By:
kouichicnakamura
Daily users:
1
Rating:
5.00
(1)
Version:
0.2.6 Last updated: 2026-09-03
Version code:
6458992
Creation date:
2026-08-03
Firefox add-on GUID:
ninja-listening-trainer-public@kouichi.example
Firefox add-on numeric ID:
3047780
Weekly download count:
1
Firefox on Android:
No
Risk:
Moderate risk impact High risk likelihood
Permissions:
Content scripts matches:
  • *.youtube.com
Size:
38.51KB
URLs:
Website
Full description:
See detailed description
Source:
Firefox Add-ons Store
Data ingested on:
2026-09-09
Compare stats and ranking:

Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.
Developed by:
kouichicnakamura
Firefox Add-ons Store
https://addons.mozilla.org/firefox/addon/ninja-listening-trainer/
Website:
https://github.com/kouichi-c-nakamura/ninja-listening-extension

User Reviews

Great tool, I'm really glad I've come across it! One annoying thing is that it covers the buttons menu on YouTube where like and dislike buttons reside, could be positioned a little higher over the buttons. And just optional, having a feature to enable pure auto-pause (besides 'record your performance') after each of the steps has ended would be nice too!
by Mo*****, 2026-09-07
View all user reviews ›

Is Ninja Listening Trainer Safe?

Risk impact
Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

Ninja Listening Trainer requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details
  • Critical Request access to the following domains: youtube.com
  • High ******* ******* **** *** ****** ***** *** ***** ** ******* **** ********* ********* ** * *********** *****
Risk likelihood
Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

Ninja Listening Trainer is recently added, and hasn't been around long enough for us to gather enough data to accurately assess its risk level.

Risk likelihood analysis details
  • High This extension was recently updated in the past month. New updates may not be stable or safe.
  • High **** ********* *** *** **** ****** ********* ********** *** *** ** ****** ** *****
  • Medium **** ********* *** ***** ** *** **** * ******* *** ********** *** *** ** ****** ** *****
  • Good **** ********* *** **** **** *******
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