diff --git a/whisperx/alignment.py b/whisperx/alignment.py
index e5d92cba..c4750cad 100644
--- a/whisperx/alignment.py
+++ b/whisperx/alignment.py
@@ -2,6 +2,7 @@
 Forced Alignment with Whisper
 C. Max Bain
 """
+
 from dataclasses import dataclass
 from typing import Iterable, Optional, Union, List
 
@@ -13,7 +14,13 @@
 
 from .audio import SAMPLE_RATE, load_audio
 from .utils import interpolate_nans
-from .types import AlignedTranscriptionResult, SingleSegment, SingleAlignedSegment, SingleWordSegment
+from .types import (
+    AlignedTranscriptionResult,
+    SingleSegment,
+    SingleAlignedSegment,
+    SingleWordSegment,
+    SegmentData,
+)
 from nltk.tokenize.punkt import PunktSentenceTokenizer, PunktParameters
 
 PUNKT_ABBREVIATIONS = ['dr', 'vs', 'mr', 'mrs', 'prof']
@@ -131,7 +138,7 @@ def align(
     # 1. Preprocess to keep only characters in dictionary
     total_segments = len(transcript)
     # Store temporary processing values
-    segment_data = {}
+    segment_data: dict[int, SegmentData] = {}
     for sdx, segment in enumerate(transcript):
         # strip spaces at beginning / end, but keep track of the amount.
         if print_progress:
diff --git a/whisperx/types.py b/whisperx/types.py
index 68f2d783..70b10a7b 100644
--- a/whisperx/types.py
+++ b/whisperx/types.py
@@ -1,4 +1,4 @@
-from typing import TypedDict, Optional, List
+from typing import TypedDict, Optional, List, Tuple
 
 
 class SingleWordSegment(TypedDict):
@@ -30,6 +30,17 @@ class SingleSegment(TypedDict):
     text: str
 
 
+class SegmentData(TypedDict):
+    """
+    Temporary processing data used during alignment.
+    Contains cleaned and preprocessed data for each segment.
+    """
+    clean_char: List[str]  # Cleaned characters that exist in model dictionary
+    clean_cdx: List[int]   # Original indices of cleaned characters
+    clean_wdx: List[int]   # Indices of words containing valid characters
+    sentence_spans: List[Tuple[int, int]]  # Start and end indices of sentences
+
+
 class SingleAlignedSegment(TypedDict):
     """
     A single segment (up to multiple sentences) of a speech with word alignment.