The CMUARCTIC dataset yields the wrong text transcripts

[rhdunn]

🐛 Describe the bug

Running:

import os
from torchaudio.datasets import CMUARCTIC

arctic = CMUARCTIC(root=os.path.join(os.getcwd(), '.download'),
                   url='slt',
                   folder_in_archive='arctic',
                   download=True)

for waveform, samplerate, transcript, utterance_id in arctic:
    print(f'{utterance_id} => {transcript}')

results in:

b0502 => And as we hurried up t
b0503 => The scents of strange vegetation blew off the tropic land.

Here, b0502 (and other utterances) have a clipped transcript. This is because the utterance contains a comma, e.g.:

( arctic_b0502 "And as we hurried up town, Joe Goose explained." )
( arctic_b0503 "The scents of strange vegetation blew off the tropic land." )

and the text is processed through a csv.reader which splits the line at the comma.

The txt.done.data files are actually scheme files where each line has the form ( utterance_id "transcription" ). It would therefore be better to use a line reader and a regular expression to extract the utterance ID and transcription.

Versions

Collecting environment information...
PyTorch version: 2.9.1+cu128
Is debug build: False
CUDA used to build PyTorch: 12.8
ROCM used to build PyTorch: N/A

OS: Ubuntu 25.10 (x86_64)
GCC version: (Ubuntu 15.2.0-4ubuntu4) 15.2.0
Clang version: Could not collect
CMake version: version 3.31.6
Libc version: glibc-2.42

Python version: 3.13.7 (main, Nov 24 2025, 20:51:28) [GCC 15.2.0] (64-bit runtime)
Python platform: Linux-6.17.0-8-generic-x86_64-with-glibc2.42
Is CUDA available: True
CUDA runtime version: 12.4.131
CUDA_MODULE_LOADING set to:
GPU models and configuration: GPU 0: NVIDIA GeForce RTX 3070 Laptop GPU
Nvidia driver version: 580.95.05
cuDNN version: Could not collect
Is XPU available: False
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: True
Caching allocator config: N/A

CPU:
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Address sizes: 39 bits physical, 48 bits virtual
Byte Order: Little Endian
CPU(s): 16
On-line CPU(s) list: 0-15
Vendor ID: GenuineIntel
Model name: 11th Gen Intel(R) Core(TM) i7-11800H @ 2.30GHz
CPU family: 6
Model: 141
Thread(s) per core: 2
Core(s) per socket: 8
Socket(s): 1
Stepping: 1
CPU(s) scaling MHz: 25%
CPU max MHz: 4600.0000
CPU min MHz: 800.0000
BogoMIPS: 4608.00
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l2 cdp_l2 ssbd ibrs ibpb stibp ibrs_enhanced tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid rdt_a avx512f avx512dq rdseed adx smap avx512ifma clflushopt clwb intel_pt avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves split_lock_detect user_shstk dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp hwp_pkg_req vnmi avx512vbmi umip pku ospke avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg avx512_vpopcntdq rdpid movdiri movdir64b fsrm avx512_vp2intersect md_clear ibt flush_l1d arch_capabilities
Virtualisation: VT-x
L1d cache: 384 KiB (8 instances)
L1i cache: 256 KiB (8 instances)
L2 cache: 10 MiB (8 instances)
L3 cache: 24 MiB (1 instance)
NUMA node(s): 1
NUMA node0 CPU(s): 0-15
Vulnerability Gather data sampling: Vulnerable
Vulnerability Ghostwrite: Not affected
Vulnerability Indirect target selection: Mitigation; Aligned branch/return thunks
Vulnerability Itlb multihit: Not affected
Vulnerability L1tf: Not affected
Vulnerability Mds: Not affected
Vulnerability Meltdown: Not affected
Vulnerability Mmio stale data: Not affected
Vulnerability Old microcode: Not affected
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed: Not affected
Vulnerability Spec rstack overflow: Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2: Mitigation; Enhanced / Automatic IBRS; IBPB conditional; PBRSB-eIBRS SW sequence; BHI SW loop, KVM SW loop
Vulnerability Srbds: Not affected
Vulnerability Tsa: Not affected
Vulnerability Tsx async abort: Not affected
Vulnerability Vmscape: Not affected

Versions of relevant libraries:
[pip3] numpy==2.3.5
[pip3] nvidia-cublas-cu12==12.8.4.1
[pip3] nvidia-cuda-cupti-cu12==12.8.90
[pip3] nvidia-cuda-nvrtc-cu12==12.8.93
[pip3] nvidia-cuda-runtime-cu12==12.8.90
[pip3] nvidia-cudnn-cu12==9.10.2.21
[pip3] nvidia-cufft-cu12==11.3.3.83
[pip3] nvidia-curand-cu12==10.3.9.90
[pip3] nvidia-cusolver-cu12==11.7.3.90
[pip3] nvidia-cusparse-cu12==12.5.8.93
[pip3] nvidia-cusparselt-cu12==0.7.1
[pip3] nvidia-nccl-cu12==2.27.5
[pip3] nvidia-nvjitlink-cu12==12.8.93
[pip3] nvidia-nvtx-cu12==12.8.90
[pip3] torch==2.9.1
[pip3] torchaudio==2.9.1
[pip3] torchcodec==0.9.1
[pip3] triton==3.5.1
[conda] Could not collect

[rhdunn]

It looks like 7d4c0bf broke this dataset. The original code was using the csv.reader as a line reader by setting the delimiter to a newline (i.e. treating newlines and delimiters the same so that the column parsing is skipped/ignored), whereas the current code is defaulting to using the comma as a delimiter and thus is splitting the line on commas in the transcription.

Looking at the Python code (https://github.com/python/cpython/blob/610aabfef2f90dc1a274703779615aa5b7fbbb3a/Modules/_csv.c#L345) it is returning the "bad delimiter value" because the delimiter is set to a newline.

It should be safe to set the delimiter to \t as:

1. that is a valid delimiter i.e. for tab separated value files;
2. running grep -P "\t" .download/arctic/*/etc/txt.done.data finds no matches.

Any other control character (e.g. \u000B for vertical tab) would also work as long as it isn't \r or \n which are being checked by the Python code.