Machine Learning Homework 2 Solution

Machine Learning HW2
Outline
● Task Introduction
● Dataset & Data Format
● Submission & Grading
Task Introduction
Task Introduction
1. Data Preprocessing: Extract MFCC features from raw waveform (already done by TAs!)
2. Classification: Perform framewise phoneme classification using pre-extracted MFCC features

Task Introduction
Task: Multiclass Classification M M M AH AH SH SH IH IH IH N N N N ...
Framewise phoneme prediction from speech.
What is a phoneme?
A unit of speech sound in a language that can serve to distinguish one word from the other.
● bat / pat , bad / bed
● Machine Learning → M AH SH IH N L ER N IH NG
Data Preprocessing

Data Preprocessing
Acoustic Features - MFCCs (Mel Frequency Cepstral Coefficients)

shape (n, 39) label
More Information About the Data
Since each frame only contains 25 ms of speech, a single frame is prev frames future frames unlikely to represent a complete phoneme
● Usually, a phoneme will span several frames
● Concatenate the neighboring phonemes for training
Finding testing labels or doing human labeling are strictly prohibited!
Introduction to Digital Speech Processing

Dataset & Data Format
Dataset
LibriSpeech (subset of train-clean-100)
● Training: 4268 preprocessed audio features with labels (total 2644158 frames)
● Testing: 1078 preprocessed audio features (total 646268 frames)
● Label: 41 classes, each class represents a phoneme
train_split.txt train_labels.txt
Data Format
● Data Format (The TAs have already extracted the features) libriphone/ features: 39-dim MFCC w/ CMVN{filename}.pt for each utterance(audio)
- train_split.txt (train metadata)
- train_labels.txt (train labels)
- test_split.txt (test metadata) - feat/
- train/
- test/
Using additional data is prohibited. Your final grade will be multiplied by 0.9!
Data Format
● Each .pt file is extracted from one original wav file
● Use torch.load() to read in .pt files as torch tensors ● Each tensor has a shape of (T, 39)
39 dims
T frames
Submission & Grading
Submission & Grading
● Leaderboard (4%): Kaggle
● Code submission (2%): NTU COOL
● Report submission (4%): Gradescope

Kaggle Public Baselines
● (1%) Simple baseline: 0.45797 (sample code)
● (1%) Medium baseline: 0.69747 (concat n frames, add layers)
● (1%) Strong baseline: 0.75028 (concat n, batchnorm, dropout, add layers)
● (1%) Boss baseline: 0.82324 (sequence-labeling(using RNN))
For boss baseline, you can refer to pervious course recording of RNN: video 1 and video 2.
Kaggle Link: https://www.kaggle.com/c/ml2022spring-hw2
● Displayed name: <student ID>_<anything>
○ e.g. b06901020_puipui

● Up to 2 submissions will be considered for the private leaderboard.


Code Submission (2%)
● Compress your code and report, then submit it to NTU COOL.
<student ID>_hw2.zip
e.g. b06901999_hw2.zip
● We can only see your last submission.
● Do not submit your model or dataset.
● If your code is not reasonable, your final grade will be multiplied by 0.9!
Report Questions
1. (2%) Implement 2 models with approximately the same number of parameters, (A) one narrower and deeper (e.g. hidden_layers=6, hidden_dim=1024) and (B) the other wider and shallower (e.g. hidden_layers=2, hidden_dim=1700). Report training/validation accuracies for both models.
2. (2%) Add dropout layers, and report training/validation accuracies with dropout rates equal to (A) 0.25/(B) 0.5/(C) 0.75 respectively.
Report Submission
● Submit with gradescope, no need to upload any files.
● We can only see your last submission.
2. Entry Code: ZR2P36
Gradescope Registration
1.
3.
Gradescope Submission

Regulations (＊) Academic Ethics Guidelines for Researchers by the
Ministry of Science and Technology
● You should NOT plagiarize, if you use any other resource, you should cite it in the reference. (＊)
● You should NOT modify your prediction files manually.
● Do NOT share codes or prediction files with any living creatures.
● Do NOT use any approaches to submit your results more than 5 times a day.
● Do NOT use additional data or pre-trained models.
● Your assignment will not be graded and your final grade x 0.9 if you violate any of the above rules.
● Prof. Lee & TAs preserve the rights to change the rules & grades.
If you have any questions, you can ask us via...
● NTU COOL (recommended)
○ https://cool.ntu.edu.tw/courses/11666
● Email
○ The title should begin with “[hwX]” (X is the homework number)
○ TBD