AN 10.72 WHILE doing four jhānas one hears sounds, versus the process of TRYING to attain four jhānas

 AN 10.72 sound is a thorn in the (four) jhanas

Notice the difference between the four jhanas (items 5-8) and item (9) nirodha attainment.

Samāpatti = attainment, trying to attain that 

vuṭṭhati = emerging from (that attainment or place)

In AN 10.72, it doesn't talk about attaining or emerging the four jhanas, whereas for nirodha it talks about attainment, or trying to attain that samadhi. 

(5) paṭhamassa jhānassa	(5) (for the) first jhāna,
saddo kaṇṭako,	noise (is a) thorn,
(6) dutiyassa jhānassa	(6) (for the) second jhāna,
vitakka-vicārā kaṇṭakā,	thought and evaluation (is a) thorn,
(7) tatiyassa jhānassa	(7) (for the) third jhāna,
pīti kaṇṭako,	Rapture (is a) thorn,
(8) catutthassa jhānassa	(8) (for the) fourth jhāna,
assāsa-passāso kaṇṭako,	In-(and)-out breathing (is a) thorn,
(9) saññā-vedayita-nirodha-samāpattiyā	(9) (for the process of attaining) perception-(and)-feelings'-cessation,
saññā ca vedanā ca kaṇṭako	perception and feeling (is a) thorn,
(10) rāgo kaṇṭako	(10) Lust (is a) thorn,
doso kaṇṭako	hatred (is a) thorn,
moho kaṇṭako.	delusion (is a) thorn.

Now compare with  SN 36.11  which deals with the same samadhis and thorns, even the same 3 arahant thorns as raga, dosa, moha as in AN 10.72.

Unlike with AN 10.72, four jhanas also specifies 'attaining', consistent with nirodho being 'attained'.

(in 4 jhānas one can perceive rūpa ✅ 🚶)

1. paṭhamaṃ jhānaṃ samāpannassa	1. (with) first jhāna attained,
🚫🗣️💬 vācā paṭip-passaddhā hoti.	🚫🗣️💬 vocalization-of-speech is pacified.
2. dutiyaṃ jhānaṃ samāpannassa	2. (with) second jhāna attained,
🚫(V&V💭) Vitakka-vicārā paṭip-passaddhā honti.	🚫(V&V💭) directed-thought-&-evaluation is pacified.
3. tatiyaṃ jhānaṃ samāpannassa	3. (with) third jhāna attained,
🚫😁 pīti paṭip-passaddhā hoti.	🚫😁 rapture is pacified.
4. catutthaṃ jhānaṃ samāpannassa	4. (with) fourth jhāna attained,
🚫🌬️😤 Assāsa-passāsā paṭip-passaddhā honti.	🚫🌬️😤 in-breath-out-breath is pacified.

(in a-rūpa / form-less attainments, body 🚶 perception disappears)

5. saññāvedayitanirodhaṃ samāpannassa	5. (with) perception-&-feeling-cessation attained,
saññā ca vedanā ca paṭip-passaddhā honti.	perception & feeling are pacified.

(standard descriptions of arahant)

6. Khīṇ-āsavassa bhikkhuno	6. (having) killed-the-asinine-inclinations, a monk’s
🚫💑 rāgo paṭip-passaddho hoti,	🚫💑 passion is pacified,
🚫😠 doso paṭip-passaddho hoti,	🚫😠 aversion is pacified,
🚫😕 moho paṭip-passaddho hotī”ti.	🚫😕 delusion is pacified.

DN 16 Buddha attaining pari nirvana, all 9 attainments he 'attains' and 'emerges from'

36. Parinibbutakathā

36. The Full nirvana

Atha kho bhagavā paṭhamaṃ jhānaṃ samāpajji, paṭhamajjhānā vuṭṭhahitvā dutiyaṃ jhānaṃ samāpajji, dutiyajjhānā vuṭṭhahitvā tatiyaṃ jhānaṃ samāpajji, tatiyajjhānā vuṭṭhahitvā catutthaṃ jhānaṃ samāpajji, catutthajjhānā vuṭṭhahitvā ākāsānañcāyatanaṃ samāpajji, ākāsānañcāyatanasamāpattiyā vuṭṭhahitvā viññāṇañcāyatanaṃ samāpajji, viññāṇañcāyatanasamāpattiyā vuṭṭhahitvā ākiñcaññāyatanaṃ samāpajji, ākiñcaññāyatanasamāpattiyā vuṭṭhahitvā nevasaññānāsaññāyatanaṃ samāpajji, nevasaññānāsaññāyatanasamāpattiyā vuṭṭhahitvā saññāvedayitanirodhaṃ samāpajji.

Then the Buddha entered the first jhāna. Emerging from that, he entered the second jhāna. Emerging from that, he successively entered into and emerged from the third jhāna, the fourth jhāna, the dimension of infinite space, the dimension of infinite consciousness, the dimension of nothingness, and the dimension of neither perception nor non-perception. Then he entered the cessation of perception and feeling.

AN 9.31 and the next 30 or so suttas following that typically mentions the 9 samadhi practices without mentioning 'attaining' or 'emerging from', or referring to them as 'attainments'.

32. Anupubbavihārasutta	32. Progressive Meditations
“Navayime, bhikkhave, anupubbavihārā.	“monks, there are these nine progressive meditations.
Katame nava?	What nine?
Paṭhamaṃ jhānaṃ, dutiyaṃ jhānaṃ, tatiyaṃ jhānaṃ, catutthaṃ jhānaṃ, ākāsānañcāyatanaṃ, viññāṇañcāyatanaṃ, ākiñcaññāyatanaṃ, nevasaññānāsaññāyatanaṃ, saññāvedayitanirodho—	The first jhāna, the second jhāna, the third jhāna, the fourth jhāna, the dimension of infinite space, the dimension of infinite consciousness, the dimension of nothingness, the dimension of neither perception nor non-perception, the cessation of perception and feeling.
ime kho, bhikkhave, nava anupubbavihārā”ti.	These are the nine progressive meditations.”

Conclusion:  in AN 10.72 sound as a thorn is being experienced WHILE in the jhānas

Comparing with all the different contexts, especially between AN 10.72 and SN 36.11 which deal with the same samadhi practices, and even the same 3 thorns for arahants removed of lust, hatred, delusion, the contrast between nirodha of perception requiring 'attaining', and the four jhanas not using the same word for 'attaining', indicates  that the thorns of sound are taking place WHILE one is doing the jhāna, and not during the attempt to attain jhāna.