The following table summarizes intangible assets as of January 31, 2024 and April 30, 2023 (in thousands):


	January 31, 2024							April 30, 2023
	Gross							Gross
	Carrying		Accumulated			Net Carrying		Carrying		Accumulated			Net Carrying
	Amount		Amortization			Amount		Amount		Amortization			Amount
Customer relationships	$	89,980	$	(77,667	)	$	12,313	$	89,980	$	(74,035	)	$	15,945
Developed software and technology		27,761		(19,697	)		8,064		31,022		(21,978	)		9,044
Patents, trademarks, and trade names		69,344		(48,541	)		20,803		68,943		(44,042	)		24,901
		187,085		(145,905	)		41,180		189,945		(140,055	)		49,890
Patents and software in development		1,663		—			1,663		1,701		—			1,701
Total definite-lived intangible assets		188,748		(145,905	)		42,843		191,646		(140,055	)		51,591
Indefinite-lived intangible assets		430		—			430		430		—			430
Total intangible assets	$	189,178	$	(145,905	)	$	43,273	$	192,076	$	(140,055	)	$	52,021

We amortize intangible assets with determinable lives over a weighted-average period of approximately five years. The weighted-average periods of amortization by intangible asset class is approximately five years for customer relationships, six years for developed software and technology, and six years for patents, trademarks, and trade names. Amortization expense amounted to $3.3 million and $3.6 million for the three months ended January 31, 2024 and 2023, respectively. Amortization expenses amounted to $9.7 million and $10.4 million for the nine months ended January 31, 2024 and 2023, respectively.